Turn off local APIC timer

This slowed down drawing to video in QEMU/VirtualBox but greatly sped up
doing so on real hardware (no longer reading from video memory).
Despite the speed-up, it is still quite slow though.

.bochsrc

@@ -1,43 +0,0 @@
-# configuration file generated by Bochs
-config_interface: textconfig
-display_library: x
-megs: 32
-romimage: file=/usr/share/bochs/BIOS-bochs-latest, address=0xf0000
-vgaromimage: /usr/share/bochs/VGABIOS-lgpl-latest
-boot: floppy
-floppya: 1_44="hos.flp", status=inserted
-# no floppyb
-ata0: enabled=1, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
-ata1: enabled=0
-ata2: enabled=0
-ata3: enabled=0
-parport1: enabled=1, file=""
-com1: enabled=1, dev=""
-usb1: enabled=1, ioaddr=0xff80, irq=10
-# no sb16
-floppy_bootsig_check: disabled=0
-vga_update_interval: 30000
-keyboard_serial_delay: 20000
-keyboard_paste_delay: 100000
-floppy_command_delay: 50000
-ips: 500000
-text_snapshot_check: 0
-mouse: enabled=0
-private_colormap: enabled=0
-i440fxsupport: enabled=0
-clock: sync=none, time0=local
-# no ne2k
-newharddrivesupport: enabled=1
-# no loader
-log: -
-logprefix: %t%e%d
-debugger_log: -
-panic: action=ask
-error: action=report
-info: action=report
-debug: action=ignore
-pass: action=fatal
-keyboard_mapping: enabled=0, map=
-keyboard_type: mf
-user_shortcut: keys=none
-# no cmosimage

.gitignore

@@ -0,0 +1,3 @@
+.rscons*
+/x86_64-elf-gcc/
+/build/

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "uefi-d"]
+	path = uefi-d
+	url = git://github.com/kubasz/uefi-d

Makefile

@@ -1,48 +0,0 @@
-# Makefile for HOS
-# Josh Holtrop
-# Created: 07/09/04
-
-FLOPPY=/dev/fd0
-FLOPPY_MOUNT=./mnt_flp
-FLOPPY_IMAGE=hos.flp
-GRUB_IMAGE=grub.flp
-
-all:
-	make -C kernel
-#	make -C rmmod
-
-clean:
-	make -C kernel clean
-	make -C include clean
-#	make -C rmmod clean
-	- rm *~ hos.flp
-
-
-grub:
-	- mkdir $(FLOPPY_MOUNT)
-	mke2fs $(FLOPPY)
-	mount -t ext2 $(FLOPPY) $(FLOPPY_MOUNT)
-	grub-install --root-directory=$(FLOPPY_MOUNT) fd0
-	umount $(FLOPPY_MOUNT)
-	- rmdir $(FLOPPY_MOUNT)
-
-grub_image:
-	dd if=$(FLOPPY) of=$(GRUB_IMAGE)
-
-install:
-	- mkdir $(FLOPPY_MOUNT)
-	mount -t ext2 $(FLOPPY) $(FLOPPY_MOUNT)
-	cp kernel/kernel.bin  $(FLOPPY_MOUNT)
-	cp menu.lst $(FLOPPY_MOUNT)/boot/grub
-	umount $(FLOPPY_MOUNT)
-	- rmdir $(FLOPPY_MOUNT)
-
-install_img:
-	- mkdir $(FLOPPY_MOUNT)
-	cp grub.flp $(FLOPPY_IMAGE)
-	mount -t ext2 -o loop $(FLOPPY_IMAGE) $(FLOPPY_MOUNT)
-	cp kernel/kernel.bin $(FLOPPY_MOUNT)
-	cp menu.lst $(FLOPPY_MOUNT)/boot/grub
-	umount $(FLOPPY_MOUNT)
-	- rmdir $(FLOPPY_MOUNT)
-

README.md

@@ -0,0 +1,71 @@
+# HOS System Requirements
+
+HOS requires:
+
+* A 64-bit CPU.
+* A UEFI system.
+* 128MB of RAM.
+
+# Building HOS
+
+From the top level of the repository, run:
+
+    ./rscons
+
+If you get errors about missing packages, install the packages and then re-run
+the build command.
+
+# Running HOS
+
+## Physical Machine
+
+To install HOS to an EFI partition, follow these steps:
+
+1. Copy build/hello/HOS.EFI to EFI partition EFI/HOS.EFI. For example, from Linux:
+
+    sudo cp build/hello/HOS.EFI /boot/efi/EFI/HOS.EFI
+
+2. Register EFI loader for HOS (one time only) with command:
+
+    efibootmgr -c -d /dev/nvme1n1 -p 2 -l '\EFI\HOS.EFI' -L HOS
+
+(Update the -d device parameter and -p partition parameter as appropriate)
+
+3. Set boot order to desired boot order. Exact order will be system dependent. Example:
+
+    efibootmgr -o 2,0,6,5
+
+At this point you should be able to boot HOS from your EFI boot selection menu.
+If you use GRUB, you can optionally create a GRUB boot entry to load HOS.EFI
+with an entry like this:
+
+    menuentry 'HOS' {
+      insmod part_gpt
+      insmod chain
+      set root='(hd0,gpt1)'
+      chainloader /EFI/HOS.EFI
+    }
+
+Just update the root setting for the correction location to your system's EFI
+partition.
+
+## VirtualBox
+
+To create a VM in VirtualBox:
+
+1. Build HOS ("./rscons").
+2. In VirtualBox, select Machine -> New.
+3. Set name to HOS.
+4. Set Type to Other.
+5. Set Version to Other/Unknown (64-bit).
+6. Click Next.
+7. Set memory size to 512 MB.
+8. Click Next.
+9. Select Do not add a virtual hard disk.
+10. Click Create.
+11. From the HOS repository, create a VirtualBox VMDK image with "./rscons mk-vmdk".
+12. Move the HOS.vmdk file generated to the HOS VirtualBox folder.
+13. In VirtualBox Manager, open HOS VM settings.
+14. Under System, check the Enable EFI checkbox.
+15. Under Storage, add a hard disk and browse to select the HOS.vmdk file.
+16. To run HOS, either start the VM through VirtualBox or with "./rscons run-vb".

Rsconscript

@@ -0,0 +1,201 @@
+require "tmpdir"
+
+project_name "HOS"
+path_prepend "x86_64-elf-gcc/bin"
+
+configure do
+  rscons "x86_64-elf-gcc.rb", "-b", "#{build_dir}/x86_64-elf-gcc"
+  check_d_compiler "ldc2", use: "ldc2"
+  check_c_compiler "x86_64-w64-mingw32-gcc", use: "x86_64-w64-mingw32-gcc"
+  check_c_compiler "x86_64-elf-gcc", use: "x86_64-elf-gcc"
+  check_c_compiler
+  check_program "mformat", on_fail: "Install the mtools package"
+  check_program "parted"
+  check_cfg package: "freetype2", on_fail: "Install libfreetype-dev", use: "freetype"
+  sh %w[git submodule update --init]
+end
+
+# Kernel default font size.
+KFONT_SIZE = 18
+
+# One kilobyte.
+KB = 1024
+
+# One megabyte.
+MB = 1024 * 1024
+
+class HulkBinObj < Builder
+  def run(options)
+    FileUtils.mkdir_p(File.dirname(@target))
+    File.write(@target, <<EOF)
+.section ".rodata"
+.balign 4096
+.global _hulk_bin_start
+_hulk_bin_start:
+.incbin "#{@sources.first}"
+.balign 4096
+.global _hulk_bin_end
+_hulk_bin_end:
+EOF
+    unless @cache.up_to_date?(@target, nil, @sources, @env)
+      print_run_message("Creating HULK binary object <target>#{@target}<reset>", nil)
+      @cache.register_build(@target, nil, @sources, @env)
+    end
+    true
+  end
+end
+
+# Create a GPT disk image with an EFI partition containing the EFI image.
+class Image < Builder
+  def run(options)
+    unless @cache.up_to_date?(@target, nil, @sources, @env)
+      print_run_message("Creating disk image <target>#{@target}<reset>", nil)
+      efi_image_size = File.stat(@sources.first).size
+      efi_image_size_mb = (efi_image_size + MB - 1) / MB
+      partition_size_mb = efi_image_size_mb + 1
+      empty_mb = "\0".b * MB
+      File.binwrite(@target, empty_mb * partition_size_mb)
+      system(*%W[mformat -i #{@target} ::])
+      system(*%W[mmd -i #{@target} ::/EFI])
+      system(*%W[mmd -i #{@target} ::/EFI/BOOT])
+      system(*%W[mcopy -i #{@target} #{@sources.first} ::/EFI/BOOT/BOOTX64.EFI])
+      partition_contents = File.binread(@target)
+      disk_image = empty_mb + partition_contents + empty_mb
+      File.binwrite(@target, disk_image)
+      system(*%W[parted --script #{@target} mklabel gpt mkpart HOS fat32 1MiB #{partition_size_mb + 1}MiB])
+      @cache.register_build(@target, nil, @sources, @env)
+    end
+    true
+  end
+end
+
+class CheckThreadLocal < Builder
+  def run(options)
+    map_file = File.binread(@sources.first)
+    if map_file =~ /\.(tdata|tbss)\b/
+      $stderr.puts "Error: found thread-local data in #{@sources.first}"
+      false
+    else
+      true
+    end
+  end
+end
+
+class FontGen < Builder
+  def run(options)
+    if @command
+      finalize_command
+    else
+      fontgen = @vars["fontgen"]
+      @sources += [fontgen]
+      command = %W[#{fontgen} #{@sources.first} #{KFONT_SIZE} #{@target}]
+      standard_command("FontGen <target>#{@target}<reset>", command, {})
+    end
+  end
+end
+
+fontgen_env = env "fontgen", use: "freetype" do |env|
+  env.Program("^/fontgen", glob("src/fontgen/**/*.c"))
+end
+
+hulk_env = env "hulk", use: %w[ldc2 x86_64-elf-gcc] do |env|
+  env.add_builder(FontGen)
+  env.add_builder(CheckThreadLocal)
+  env.FontGen("^/src/hulk/kfont.d", "font/Hack-Regular.ttf",
+              "fontgen" => fontgen_env.expand("^/fontgen"))
+  env["sources"] = glob("src/hulk/**/*.d")
+  env["sources"] << "^/src/hulk/kfont.d"
+  cpu_attrs = %w[
+    -avx
+    -avx2
+    -avx512bf16
+    -avx512bitalg
+    -avx512bw
+    -avx512cd
+    -avx512dq
+    -avx512er
+    -avx512f
+    -avx512ifma
+    -avx512pf
+    -avx512vbmi
+    -avx512vbmi2
+    -avx512vl
+    -avx512vnni
+    -avx512vp2intersect
+    -avx512vpopcntdq
+    -sse
+    -sse-unaligned-mem
+    -sse2
+    -sse3
+    -sse4.1
+    -sse4.2
+    -sse4a
+    -ssse3
+  ]
+  env["DFLAGS"] += %W[-mtriple=x86_64-unknown-elf -mattr=#{cpu_attrs.join(",")} --betterC -release -O3 --wi --enable-cross-module-inlining -code-model=large]
+  env["D_IMPORT_PATH"] += %w[src]
+  env["D_IMPORT_PATH"] << env.expand("^/src")
+  env["LD"] = "x86_64-elf-gcc"
+  env["LDFLAGS"] += %w[-nostdlib -Tsrc/hulk/hulk.ld -Wl,-Map,${_TARGET}.map]
+  env["LDCMD"] = %w[${LD} -o ${_TARGET} ${LDFLAGS} ${_SOURCES} ${LIBDIRPREFIX}${LIBPATH} ${LIBLINKPREFIX}${LIBS}]
+  env["OBJDUMP"] = "x86_64-elf-objdump"
+  env["OBJCOPY"] = "x86_64-elf-objcopy"
+  env.Program("^/hulk.elf", "${sources}")
+  env.produces("^/hulk.elf", "^/hulk.elf.map")
+  env.CheckThreadLocal(:hulk_map_check, "^/hulk.elf.map")
+  env.depends("^/hulk.elf", "src/hulk/hulk.ld")
+  env["SIZE"] = "x86_64-elf-size"
+  env.Size("^/hulk.size", "^/hulk.elf")
+  env.Disassemble("^/hulk.txt", "^/hulk.elf")
+  env.Command("^/hulk.bin", "^/hulk.elf",
+              "CMD" => %W[${OBJCOPY} -O binary ${_SOURCES} ${_TARGET}],
+              "CMD_DESC" => "Convert ELF to binary:")
+  env.add_build_hook do |builder|
+    if builder.target.end_with?(".o")
+      env.Disassemble("#{builder.target}.txt", builder.target)
+    end
+  end
+end
+
+hello_env = env "hello", use: %w[ldc2 x86_64-w64-mingw32-gcc] do |env|
+  env.add_builder(Image)
+  env.add_builder(CheckThreadLocal)
+  env.add_builder(HulkBinObj)
+  env["sources"] = glob("src/hello/**/*.d")
+  env["sources"] += glob("uefi-d/source/**/*.d")
+  env.HulkBinObj("^/hulk_bin.S", hulk_env.expand("^/hulk.bin"))
+  env.Object("^/hulk_bin.o", "^/hulk_bin.S")
+  env.depends("^/hulk_bin.o", hulk_env.expand("^/hulk.bin"))
+  env["sources"] << "^/hulk_bin.o"
+  env["DFLAGS"] += %w[-mtriple=x86_64-unknown-windows-coff --betterC -release -O3 --wi --enable-cross-module-inlining]
+  env["D_IMPORT_PATH"] += %w[src uefi-d/source]
+  env["LD"] = "x86_64-w64-mingw32-gcc"
+  env["LDFLAGS"] += %w[-nostdlib -Wl,-dll -shared -Wl,--subsystem,10 -e efi_main -Wl,-Map,${_TARGET}.map]
+  env["LDCMD"] = %w[${LD} -o ${_TARGET} ${LDFLAGS} ${_SOURCES} ${LIBDIRPREFIX}${LIBPATH} ${LIBLINKPREFIX}${LIBS}]
+  env["OBJDUMP"] = "x86_64-w64-mingw32-objdump"
+  env.Program("^/HOS.EFI", "${sources}")
+  env.produces("^/HOS.EFI", "^/HOS.EFI.map")
+  env.CheckThreadLocal(:hos_map_check, "^/HOS.EFI.map")
+  env["SIZE"] = "x86_64-w64-mingw32-size"
+  env.Size("^/HOS.size", "^/HOS.EFI")
+  env.Disassemble("^/HOS.txt", "^/HOS.EFI")
+  env.Image("^/HOS.img", "^/HOS.EFI")
+end
+
+task "run", desc: "Run HOS in QEMU" do
+  Dir.mktmpdir do |tmpdir|
+    img = hello_env.expand("^/HOS.img")
+    FileUtils.cp(img, tmpdir)
+    sh %W[qemu-system-x86_64 -cpu max -bios OVMF.fd -drive file=#{tmpdir}/HOS.img,format=raw -device qemu-xhci -device usb-tablet]
+  end
+end
+
+# See README.md for how to set up VirtualBox for HOS.
+task "mk-vmdk", desc: "Create VirtualBox VMDK virtual drive for HOS" do
+  sh %W[VBoxManage internalcommands createrawvmdk -filename HOS.vmdk -rawdisk #{File.expand_path(hello_env.expand("^/HOS.img"))}]
+end
+
+# See README.md for how to set up VirtualBox for HOS.
+task "run-vb", desc: "Run HOS in VirtualBox" do
+  sh %W[VBoxManage startvm HOS]
+end

include/Makefile

@@ -1,2 +0,0 @@
-clean:
-	- rm *~

include/kernel.h

@@ -1,23 +0,0 @@
-
-#ifndef __HOS_KERNEL_H__
-#define __HOS_KERNEL_H__ __HOS_KERNEL_H__
-
-#include "multiboot.h"
-
-#define VIRT_OFFSET 0xC0000000
-#define MAX_MODULES 16
-#define MAX_MMAP 16
-
-typedef unsigned int u32_t;
-typedef unsigned short u16_t;
-typedef unsigned char u8_t;
-
-/* returns true to callee if we should jump to a real mode module */
-int k_mbsave(mb_info_t *mbinfo, unsigned int mb_magic);
-
-void k_init();
-
-void isr();
-
-#endif
-

include/module.h

@@ -1,16 +0,0 @@
-
-#ifndef __HOS_MODULE_H__
-#define __HOS_MODULE_H__ __HOS_MODULE_H__
-
-#define MOD_REAL_MODE 1
-#define MOD_KERNEL 2
-
-typedef struct {
-	unsigned int mod_magic;		// "HOSM" = 0x484F534D
-	unsigned int mod_type;		// module type
-	void (*init) ();		// address of void initialization function
-	unsigned int reserved;
-} hos_module_header_t;
-
-#endif
-

include/multiboot.h

@@ -1,144 +0,0 @@
-
-#ifndef __HOS_MULTIBOOT_H__
-#define __HOS_MULTIBOOT_H__ __HOS_MULTIBOOT_H__
-
-/* The magic number for the Multiboot header. */
-#define MULTIBOOT_HEADER_MAGIC          0x1BADB002
-
-#define MB_HEADER_ALIGN_MODULES 0x01
-#define MB_HEADER_MEM_INFO 0x02
-#define MB_HEADER_VIDEO_INFO 0x04
-#define MB_HEADER_KLUDGE_OFFSETS 0x10000
-
-
-/* The magic number passed by a Multiboot-compliant boot loader. */
-#define MULTIBOOT_BOOTLOADER_MAGIC      0x2BADB002
-
-#define MB_BOOTLOADER_MEM_INFO 0x01
-#define MB_BOOTLOADER_BOOT_DEVICE 0x02
-#define MB_BOOTLOADER_COMMAND_LINE 0x04
-#define MB_BOOTLOADER_MODS 0x08
-#define MB_BOOTLOADER_AOUT 0x10
-#define MB_BOOTLOADER_ELF 0x20
-#define MB_BOOTLOADER_MMAP 0x40
-#define MB_BOOTLOADER_DRIVES 0x80
-#define MB_BOOTLOADER_CONFIG 0x0100
-#define MB_BOOTLOADER_APM 0x0200
-#define MB_BOOTLOADER_GRAPHICS 0x0400
-
-
-#define MB_DRIVE_MODE_CHS 0
-#define MB_DRIVE_MODE_LBA 1
-
-
-/* The Multiboot header. */
-typedef struct
-{
-	unsigned int magic;
-	unsigned int flags;
-	unsigned int checksum;
-	unsigned int header_addr;
-	unsigned int load_addr;
-	unsigned int load_end_addr;
-	unsigned int bss_end_addr;
-	unsigned int entry_addr;
-} mb_header_t;
-
-/* The symbol table for a.out. */
-typedef struct
-{
-	unsigned int tabsize;
-	unsigned int strsize;
-	unsigned int addr;
-	unsigned int reserved;
-} mb_aout_symbol_table_t;
-
-/* The section header table for ELF. */
-typedef struct
-{
-	unsigned int num;
-	unsigned int size;
-	unsigned int addr;
-	unsigned int shndx;
-} mb_elf_section_header_table_t;
-
-/* The Multiboot information. */
-typedef struct
-{
-	unsigned int flags;
-	unsigned int mem_lower;		// present if flags[0] is set
-	unsigned int mem_upper;
-	unsigned int boot_device;	// 1
-	unsigned int cmdline;		// 2
-	unsigned int mods_count;	// 3
-	unsigned int mods_addr;
-	union
-	{
-		mb_aout_symbol_table_t aout_sym;	// 4
-		mb_elf_section_header_table_t elf_sec;	// 5
-	};
-	unsigned int mmap_length;	// 6
-	unsigned int mmap_addr;
-	unsigned int drives_length;	// 7
-	unsigned int drives_addr;
-	unsigned int config_table;	// 8
-	unsigned int bootloader_name;	// 9
-	unsigned int apm_table;		// 10
-
-	unsigned int vbe_control_info;	// 11
-	unsigned int vbe_mode_info;
-	unsigned short vbe_mode;
-	unsigned short vbe_interface_seg;
-	unsigned short vbe_interface_off;
-	unsigned short vbe_interface_len;
-} mb_info_t;
-
-/* The module structure. */
-typedef struct
-{
-	unsigned int mod_start;
-	unsigned int mod_end;
-	unsigned int string;
-	unsigned int reserved;
-} mb_module_t;
-
-/* The memory map. Be careful that the offset 0 is base_addr_low, not size. */
-typedef struct
-{
-	unsigned int size;		//offset -4
-	unsigned int base_addr_low;	//offset 0
-	unsigned int base_addr_high;
-	unsigned int length_low;
-	unsigned int length_high;
-	unsigned int type;
-} mb_mmap_t;
-
-/* The drive structure */
-typedef struct
-{
-	unsigned int size;
-	unsigned char drive_number;
-	unsigned char drive_mode;
-	unsigned char drive_cylinders;
-	unsigned char drive_heads;
-	unsigned char drive_sectors;
-	unsigned short drive_ports[1];
-} mb_drive_t;
-
-/* APM table structure */
-typedef struct
-{
-	unsigned short version;
-	unsigned short cseg;
-	unsigned int offset;
-	unsigned short cseg_16;
-	unsigned short dseg;
-	unsigned short flags;
-	unsigned short cseg_len;
-	unsigned short cseg_16_len;
-	unsigned short dseg_len;
-} mb_apm_t;
-
-
-#endif
-

kernel/Makefile

@@ -1,33 +0,0 @@
-# Makefile for HOS
-# Josh Holtrop
-# Created: 07/08/04
-# Modified: 07/09/04
-
-# Assembler Information:
-NASM=nasm
-NASM_FLAGS=-f aout
-
-# C Information:
-CC=gcc
-CC_FLAGS=-fleading-underscore -fno-builtin -nostdlib -nostartfiles -nodefaultlibs -I. -I../include -Wall
-
-# Linker Information:
-LD=ld
-LD_FLAGS=-nodefaultlibs -nostdlib --no-demangle -T link.ld
-
-all: Asm_Kernel C_Kernel
-	$(LD) $(LD_FLAGS) -Map boot.map boot.o kernel.o -o kernel.bin
-
-Asm_Kernel:
-	$(NASM) $(NASM_FLAGS) -l boot.lst boot.asm -o boot.o
-
-C_Kernel:
-	$(CC) $(CC_FLAGS) -c kernel.c -o kernel.o
-
-#################################################
-# Clean up the source directory of any binaries #
-#################################################
-clean:
-	- rm *.s *.S *.o *.bin *~ *.map *.lst
-
-

kernel/boot.asm

@@ -1,196 +0,0 @@
-;boot.asm
-;Author: Josh Holtrop
-;Date: 07/08/04
-;Modified: 07/10/04
-
-
-%define	MULTIBOOT_MAGIC	0x1BADB002
-%define	MULTIBOOT_FLAGS	0x00010003
-
-%define VIRT_OFFSET	0xC0000000	;3gb virtual address
-%define PHYS_START	0x00100000	;1mb physical address
-%define VIRT_STACK_TOP	0xCFFFFFFC	;3gb+256mb virtual address
-%define GDT_P	PHYS_START		;1mb physical - Global Descriptor Table space
-%define GDT_V	GDT_P+VIRT_OFFSET
-%define IDT_P	PHYS_START+0x2000	;1mb+8kb - Interrupt Descriptor Table space
-%define IDT_V	IDT_P+VIRT_OFFSET
-%define PDBR_P	PHYS_START+0x4000	;1mb+16kb - Page Directory Base Register (first PD)
-%define PDBR_V	PDBR_P+VIRT_OFFSET
-%define LOPT_P	PHYS_START+0x5000	;1mb+20kb - LOw Page Table for mapping first 4mb
-%define LOPT_V	LOPT_P+VIRT_OFFSET
-%define PT_STACK_P PHYS_START+0x6000	;1mb+24kb - page table for initial kernel stack pages (under 0xD0000000)
-%define PT_STACK_V PT_STACK_P+VIRT_OFFSET
-%define STACK_P	PHYS_START+0x7000	;1mb+28kb - initial 4kb kernel stack page
-%define STACK_V	STACK_P+VIRT_OFFSET
-%define KERNEL_P PHYS_START+0x8000	;1mb+32kb - the kernel's physical address
-%define KERNEL_V KERNEL_P+VIRT_OFFSET	;3gb+1mb+32kb, the virtual address of the kernel
-
-extern _k_init, _isr, _k_mbsave, _end
-
-[bits 32]
-
-[global _start]
-_start:
-
-multiboot_header:
-	dd	MULTIBOOT_MAGIC					;magic
-	dd	MULTIBOOT_FLAGS					;flags
-	dd	-(MULTIBOOT_MAGIC + MULTIBOOT_FLAGS)		;checksum
-
-	dd	multiboot_header-VIRT_OFFSET			;header_addr
-	dd	_start-VIRT_OFFSET				;load_addr
-	dd	0						;load_end_addr
-	dd	_end-VIRT_OFFSET				;bss_end_addr
-	dd	multiboot_entry-VIRT_OFFSET			;entry_addr
-
-;	dd	1						;mode_type
-;	dd	80						;width
-;	dd	25						;height
-;	dd	0						;depth
-
-[global multiboot_entry]
-multiboot_entry:
-;This is where the kernel begins execution from the bootloader.
-;At this point, a temporary gdt is set up to "map" 0xC000_0000 to 0x0.
-	cli					;should already be off...
-	lgdt	[gdtrbs32-VIRT_OFFSET]
-	jmp	KERNEL_CODE_BS32:segmented_start
-segmented_start:
-	mov	ax, KERNEL_DATA_BS32
-	mov	ss, ax
-	mov	ds, ax
-	mov	es, ax
-	mov	gs, ax
-	mov	fs, ax
-	mov	esp, STACK_V+0x1000		;ok, now we can access our data
-
-;aloop:
-;	inc dword [0xC00B8000]
-;	jmp	aloop
-
-
-;Then the multiboot info structures are saved to local data variables.
-	add	ebx, VIRT_OFFSET
-	push	eax
-	push	ebx				;pointer to multiboot info structure
-	call	_k_mbsave			;save multiboot info structures
-	add	esp, 8
-
-	cmp	eax, 0
-	jz	pm_return
-
-;go back to real mode to initialize video mode
-	mov	ebx, pm_return
-
-
-
-;Next we enable paging with the first 4mb mapped 1:1 virtual:physical
-; and with the 4mb starting at 0xC000_0000 mapped to the first 4mb physical.
-pm_return:
-	xor	eax, eax
-	mov	edi, PDBR_V
-	mov	ecx, 1024			;clear the PDBR
-	rep stosd
-	mov	edi, PT_STACK_V
-	mov	ecx, 1024			;clear the PT_STACK
-	rep stosd
-	mov	[PDBR_V], dword LOPT_P|0x03		;store the physical address of the LOw Page Table | (read/write, present)
-	mov	[PDBR_V+0xC00], dword LOPT_P|0x03	;store the physical address of the LOw Page Table | (read/write, present)
-	mov	[PDBR_V+0xCFC], dword PT_STACK_P|0x03	;store the physical address of the initial stack page page table | (read/write, present)
-	mov	[PT_STACK_V+0xFFC], dword STACK_P|0x03	;store the physical address of the initial stack page | (read/write, present)
-
-	mov	edi, LOPT_V
-	mov	ecx, 1024
-	mov	eax, 0x03			;starting physical address = 0x0 | (read/write, present flags)
-fill_lopt_loop:					;fill the page table
-	stosd
-	add	eax, 4096			;increment next phsyical address by 4kb
-	loop	fill_lopt_loop
-
-	mov	eax, PDBR_P
-	mov	cr3, eax			;store the Page Directory Base Address
-	mov	eax, cr0
-	or	eax, 0x80000000			;set Page Enable bit
-	mov	cr0, eax			;now paging is active!
-
-
-	mov	edi, GDT_V
-	mov	esi, gdt
-	mov	ecx, gdt_end-gdt
-	rep movsb
-
-	mov	edi, IDT_V		;destination
-	mov	esi, isr_0		;address of isr0
-	mov	edx, isr_1-isr_0	;distance between isr labels
-	mov	ecx, 50			;number of isrlabels
-fill_idt:
-	mov	ebx, esi
-	mov	ax, si
-	stosw				;0 offset 15:0
-	mov	ax, KERNEL_CODE
-	stosw				;2 selector 15:0
-	mov	ax, 0x8E00
-	stosw				;4 [P][DPL][0][TYPE][0][0][0][0][0][0][0][0]
-	shr	esi, 16
-	mov	ax, si
-	stosw				;6 offset 31:16
-	mov	esi, ebx
-	add	esi, edx
-	loop	fill_idt
-	mov	word	[IDT_V+0x30*8+4], 0xEE00	;interrupt 0x30 has user priviledges
-
-;Then we can start using our "real" gdt, then unmap the lower 4mb.
-	lgdt	[gdtr]			;load gdt
-	jmp	KERNEL_CODE:newgdtcontinue
-newgdtcontinue:
-	mov	ax, KERNEL_DATA
-	mov	es, ax
-	mov	ds, ax
-	mov	gs, ax
-	mov	fs, ax
-	mov	ss, ax
-	mov	esp, VIRT_STACK_TOP		;stack just under 3gb+256mb, moves downward
-	lidt	[idtr]				;load idt
-	mov	[PDBR_V], dword 0		;unmap 0x0, we are running completely paged at 0xC000_0000
-
-	call	_k_init			;C kernel initialization
-
-idle_loop:
-;	sti
-	hlt
-	jmp	idle_loop
-
-;-------------------------------------------------------
-gdtrbs32:
-	dw	gdt_endbs32-gdtbs32-1
-	dd	gdtbs32-VIRT_OFFSET
-gdtbs32:				;null descriptor
-	dd	0
-	dd	0
-
-	;a base of 0x4000_0000, when added to 0xC000_0000 will produce 0x0000_0000 physical before paging in effect
-KERNEL_CODE_BS32 equ $-gdtbs32
-	db	0xff		;limit	7:0
-	db	0xff		;limit	15:8
-	db	0x00		;base	7:0
-	db	0x00		;base	15:8
-	db	0x00		;base	23:16
-	db	0x9a		;access
-	db	0xcf		;flags / limit 19:16
-	db	0x40		;base	31:24
-
-KERNEL_DATA_BS32 equ $-gdtbs32
-	db	0xff		;limit	7:0
-	db	0xff		;limit	15:8
-	db	0x00		;base	7:0
-	db	0x00		;base	15:8
-	db	0x00		;base	23:16
-	db	0x92		;access
-	db	0xcf		;flags / limit 19:16
-	db	0x40		;base	31:24
-
-gdt_endbs32:
-
-%include "gdt.inc"
-%include "idt.inc"
-

kernel/gdt.inc

@@ -1,71 +0,0 @@
-;gdt.inc
-;Author: Josh Holtrop
-;Date: 10/30/03
-;Modified: 03/02/04
-
-gdtr:
-	dw	gdt_end-gdt-1
-	dd	GDT_V
-gdt:
-	dd	0
-	dd	0
-KERNEL_CODE equ $-gdt
-	dw	0xffff	;limit 15:0
-	dw	0x0000	;base  15:0
-	db	0x00	;base  23:16
-	db	0x9A	;access ([P][DPL][1][Executable][Direction/Conforming][Writable/Readable][A])
-	db	0xCF	;flags ([G][D/B][0][0]) / limit 19:16
-	db	0x00	;base  31:24
-KERNEL_DATA equ $-gdt
-	dw	0xffff	;limit 15:0
-	dw	0x0000	;base  15:0
-	db	0x00	;base  23:16
-	db	0x92	;access ([P][DPL][1][Executable][Direction/Conforming][Writable/Readable][A])
-	db	0xCF	;flags ([G][D/B][0][0]) / limit 19:16
-	db	0x00	;base  31:24
-USER_CODE equ $-gdt
-	dw	0xffff	;limit 15:0
-	dw	0x0000	;base  15:0
-	db	0x00	;base  23:16
-	db	0xFA	;access ([P][DPL][1][Executable][Direction/Conforming][Writable/Readable][A])
-	db	0xCF	;flags ([G][D/B][0][0]) / limit 19:16
-	db	0x00	;base  31:24
-USER_DATA equ $-gdt
-	dw	0xffff	;limit 15:0
-	dw	0x0000	;base  15:0
-	db	0x00	;base  23:16
-	db	0xF2	;access ([P][DPL][1][Executable][Direction/Conforming][Writable/Readable][A])
-	db	0xCF	;flags ([G][D/B][0][0]) / limit 19:16
-	db	0x00	;base  31:24
-VESA_CODE equ $-gdt
-	dw	0xffff	;limit 15:0
-	dw	0x0000	;base  15:0
-	db	0x00	;base  23:16
-	db	0x9A	;access ([P][DPL][1][Executable][Direction/Conforming][Writable/Readable][A])
-	db	0x40	;flags ([G][D/B][0][0]) / limit 19:16
-	db	0x00	;base  31:24
-VESA_DATA equ $-gdt
-	dw	0xffff	;limit 15:0
-	dw	0x0000	;base  15:0
-	db	0x00	;base  23:16
-	db	0x92	;access ([P][DPL][1][Executable][Direction/Conforming][Writable/Readable][A])
-	db	0x40	;flags ([G][D/B][0][0]) / limit 19:16
-	db	0x00	;base  31:24
-VIDEO_TEXT equ $-gdt
-	dw	0x7FFF	;limit 15:0
-	dw	0x8000	;base  15:0
-	db	0x0B	;base  23:16
-	db	0x92	;access ([P][DPL][1][Executable][Direction/Conforming][Writable/Readable][A])
-	db	0x40	;flags ([G][D/B][0][0]) / limit 19:16
-	db	0x00	;base  31:24
-VIDEO_GRAPHICS equ $-gdt
-	dw	0xFFFF	;limit 15:0
-	dw	0x0000	;base  15:0
-	db	0x0A	;base  23:16
-	db	0x92	;access ([P][DPL][1][Executable][Direction/Conforming][Writable/Readable][A])
-	db	0x40	;flags ([G][D/B][0][0]) / limit 19:16
-	db	0x00	;base  31:24
-gdt_end:
-
-
-

kernel/idt.inc

@@ -1,92 +0,0 @@
-;idt.inc
-;Author: Josh Holtrop
-;Date: 10/30/03
-;Modified: 07/06/04
-
-idtr:
-	dw	50*8-1		;size of idt
-	dd	IDT_V		;address of idt
-
-
-%macro isr_label 1
-isr_%1:
-	push	eax
-	mov	eax, %1
-	jmp	isr_main
-%endmacro
-
-isr_label	0
-isr_label	1
-isr_label	2
-isr_label	3
-isr_label	4
-isr_label	5
-isr_label	6
-isr_label	7
-isr_label	8
-isr_label	9
-isr_label	10
-isr_label	11
-isr_label	12
-isr_label	13
-isr_label	14
-isr_label	15
-isr_label	16
-isr_label	17
-isr_label	18
-isr_label	19
-isr_label	20
-isr_label	21
-isr_label	22
-isr_label	23
-isr_label	24
-isr_label	25
-isr_label	26
-isr_label	27
-isr_label	28
-isr_label	29
-isr_label	30
-isr_label	31
-isr_label	32
-isr_label	33
-isr_label	34
-isr_label	35
-isr_label	36
-isr_label	37
-isr_label	38
-isr_label	39
-isr_label	40
-isr_label	41
-isr_label	42
-isr_label	43
-isr_label	44
-isr_label	45
-isr_label	46
-isr_label	47
-isr_label	48
-isr_label	49
-
-isr_main:
-	pusha
-	push	ds
-	push	es
-
-	push	eax	;interrupt number
-	call	_isr
-	add	esp, 4
-
-	pop	es
-	pop	ds
-	popa
-	pop	eax		;original saved eax
-
-	iret
-
-
-
-
-
-
-
-
-

kernel/kernel.c

@@ -1,76 +0,0 @@
-
-#include "kernel.h"
-#include "multiboot.h"
-#include "module.h"
-
-mb_info_t mb_info_block;
-mb_mmap_t mb_mmap[MAX_MMAP];
-mb_module_t mb_modules[MAX_MODULES];
-mb_apm_t mb_apm_table;
-char mb_cmdline[256];
-
-/* This function runs in segmented memory - 0xC000_0000 is mapped to 0x0 but 0x0
-   itself is an invalid linear address. Therefore, the multiboot information addresses
-   must be manually adjusted by VIRT_OFFSET to become valid linear addresses. */
-int k_mbsave(mb_info_t *mbinfo, unsigned int mb_magic)
-{
-	if (mb_magic != MULTIBOOT_BOOTLOADER_MAGIC)
-	{
-		char *msg = "Bad multiboot magic identifier!";
-		char *dest = (char *) 0xC00B8000;
-		while (*msg)
-		{
-			*dest++ = *msg++;
-			*dest++ = 0x04;		//red error message
-		}
-		for (;;) ;
-	}
-	mb_info_block = *mbinfo;
-	if (mb_info_block.flags & MB_BOOTLOADER_COMMAND_LINE)
-	{
-		mb_info_block.cmdline += VIRT_OFFSET;
-		memcpy(mb_cmdline, mb_info_block.cmdline, 256);
-		mb_cmdline[255] = 0;
-	}
-	if (mb_info_block.flags & MB_BOOTLOADER_MODS)
-	{
-		mb_info_block.mods_addr += VIRT_OFFSET;
-		int i;
-		for (i = 0; i < mb_info_block.mods_count && i < MAX_MODULES; i++)
-		{
-			mb_modules[i] = ((mb_module_t *)mb_info_block.mods_addr)[i];
-		}
-	}
-	if (mb_info_block.flags & MB_BOOTLOADER_MMAP)
-	{
-		mb_info_block.mmap_addr += VIRT_OFFSET - 4;	//-4 to get to size field, not base_addr_low field
-		mb_mmap_t *mmap = (mb_mmap_t *)mb_info_block.mmap_addr;
-		int i, sz = 0;
-		for (i = 0; sz < mb_info_block.mmap_length && i < MAX_MMAP; i++)
-		{
-			sz += mmap->size;
-			mb_mmap[i] = *mmap;
-			mmap = (mb_mmap_t *)(((u32_t) mmap) + mmap->size);
-		}
-	}
-	if (mb_info_block.flags & MB_BOOTLOADER_APM)
-	{
-		mb_info_block.apm_table += VIRT_OFFSET;
-		mb_apm_table = *(mb_apm_t *)mb_info_block.apm_table;
-	}
-	return 0;
-}
-
-void k_init()
-{
-	for (;;)
-	{
-		(*(char*)0xC00B8000)++;
-	}
-}
-
-void isr()
-{
-	for (;;) ;
-}
-

kernel/link.ld

@@ -1,26 +0,0 @@
-OUTPUT_FORMAT("binary")
-ENTRY(_start)
-SECTIONS
-{
-  .text  0xC0108000 : {
-    code = .; _code = .; __code = .;
-    *(.text)
-    . = ALIGN(4096);
-  }
-  .data  : {
-    data = .; _data = .; __data = .;
-    *(.data)
-/*    . = ALIGN(4096); */
-  }
-  .rodata  : {
-    rodata = .; _rodata = .; __rodata = .;
-    *(.rodata)
-    . = ALIGN(4096);
-  }
-  .bss  : {
-    bss = .; _bss = .; __bss = .;
-    *(.bss)
-    . = ALIGN(4096);
-  }
-  end = .; _end = .; __end = .;
-}

menu.lst

@@ -1,9 +0,0 @@
-
-timeout 10
-default 0
-
-title HOS 0.15
-root (fd0)
-kernel /kernel.bin
-
-

readme.txt

@@ -0,0 +1,89 @@
+HOS - Holtrop's Operating System
+--------------------------------
+
+HOS is (in the process of becoming) a 32-bit, protected mode, graphical, multitasking operating system.
+It was written by me, Josh Holtrop, with help from a few others along the way.
+
+
+Goals: (A = accomplished, P = in progress, T = todo)
+----------------------------------------------------
+(A) Custom bootloader to load kernel from FAT-formatted boot media, options for video mode/ram disk
+(A) Multiboot compliance - kernel can be loaded by GRUB
+(A) 32-bit protected mode environment
+(A) VESA Support for graphics modes
+(A) PS/2 keyboard & mouse drivers
+(A) Utilize x86's paging architecture for virtual memory management
+
+(P) Console Manager
+(P) VFS abstraction layer for a single file system
+(P) ram disk driver
+(P) devfs file system driver
+(P) ext2 file system support
+
+(T) vfat file system support
+(T) Multitasking support
+(T) HASH command shell
+(T) Window Manager
+(T) Various other utilities/applications
+(T) Hard Drive (ATA) driver
+(T) cdrom (ATAPI) driver
+
+
+Change Log
+----------
+0.16
+12/16/04 - initrd going to be loaded as a gzipped ext2 image (kernel module) - faster loading!
+
+0.15
+07/10/04 - Multiboot support added, loadable by GRUB
+
+0.14
+05/21/04 - C++ support in kernel, can use classes & templates
+04/04/04 - video_line function for diagonal lines
+03/16/04 - new VFS design with support for a loop device
+03/01/04 - Thanks to Ben Meyer for helping me get a Makefile working and building on linux to work!
+
+0.13
+01/26/04 - functions added to read/write CMOS clock date and time
+01/19/04 - fixed bug GDTR/IDTR pointing to physical rather than linear table base address
+01/07/04 - fixed bug not reading sectors correctly from floppy
+12/28/03 - fixed bug not storing eax on interrupt
+12/25/03 - fixed bug in mm_palloc()
+12/25/03 - incorporated output functions as regular functions rather than as part of a linked library
+12/23/03 - re-written physical memory manager using bitmap instead of stack
+12/22/03 - kernel relocated to 3gb linear / 1mb+24kb physical to allow for app. address space
+
+0.12
+12/21/03 - sample bmp loader tested, works (tests loading a kernel of size ~ 932kb)
+12/20/03 - GDT/IDT now located at 1mb physical, before kernel
+10/30/03 - turns floppy motor off
+10/30/03 - keyboard LEDs working
+10/29/03 - paging functions working
+10/15/03 - physical memory management page allocators working
+
+0.11
+10/09/03 - PS/2 mouse driver
+
+0.10
+09/11/03 - Rewritten C and assembly kernel with VESA GUI mode support, keyboard driver
+
+0.05
+05/14/03 - HGUI24/HGUI32 commands finished for testing GUI on both 24bpp and 32bpp graphics cards
+05/14/03 - first web release!
+
+0.04
+03/09/03 - added VM shortcut command
+03/09/03 - press up to fill retrieve last inputted command for Nate Scholten
+03/08/03 - press clear to clear console input
+03/07/03 - added "shortcut" commands PC, IC, ? for Nate Scholten
+03/06/03 - added PROMPTC, INPUTC commands
+
+0.03
+12/30/02 - Command Line Interface working, accepting basic commands
+
+0.02
+12/11/02 - Assembly bootsector can load stage2 ("console")
+
+0.01
+12/01/02 - Real mode assembly bootsector boots from floppy disk successfully
+

rscons

@@ -0,0 +1,46 @@
+#!/usr/bin/env ruby
+
+# Copyright (c) 2013-2022 Josh Holtrop
+#
+# MIT License
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+
+script = File.join(File.dirname(__FILE__), ".rscons-3.1.0-4892f95d56c30bbe9aa0c9964062ec5b.rb")
+unless File.exist?(script)
+  if File.read(__FILE__, mode: "rb") =~ /^#==>(.*)/
+    require "zlib"
+    require "base64"
+    encoded_compressed = $1
+    unescaped_compressed = Base64.decode64(encoded_compressed)
+    inflated = Zlib::Inflate.inflate(unescaped_compressed)
+    File.open(script, "wb") do |fh|
+      fh.write(inflated)
+    end
+  else
+    raise "Could not decompress."
+  end
+end
+load script
+if __FILE__ == $0
+  Rscons::Cli.new.run(ARGV)
+end
+#==>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 truncated

src/fontgen/fontgen.c

@@ -0,0 +1,173 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <ft2build.h>
+#include <stdio.h>
+#include FT_FREETYPE_H
+#include <string.h>
+#include <strings.h>
+#include <ctype.h>
+
+#define N_CHARS 128
+
+#define round_up_26_6(val) (((val) + 63) >> 6u)
+
+int max_advance;
+int max_top = -9999;
+int min_bottom = 9999;
+int line_height;
+int baseline_offset;
+
+typedef struct {
+    int width;
+    int height;
+    int top;
+    int left;
+    uint8_t * bitmap;
+} char_info_t;
+
+static char_info_t char_infos[N_CHARS];
+
+static void load_char(FT_Face face, int char_code)
+{
+    if (FT_Load_Char(face, char_code, FT_LOAD_RENDER) != 0)
+    {
+        return;
+    }
+    int advance = round_up_26_6(face->glyph->advance.x);
+    if (advance > max_advance)
+    {
+        max_advance = advance;
+    }
+    if ((face->glyph->bitmap.width == 0) ||
+            (face->glyph->bitmap.rows == 0))
+    {
+        return;
+    }
+    char_infos[char_code].width = face->glyph->bitmap.width;
+    char_infos[char_code].height = face->glyph->bitmap.rows;
+    char_infos[char_code].top = face->glyph->bitmap_top;
+    if (char_infos[char_code].top > max_top)
+    {
+        max_top = char_infos[char_code].top;
+    }
+    int bottom = char_infos[char_code].top - char_infos[char_code].height;
+    if (bottom < min_bottom)
+    {
+        min_bottom = bottom;
+    }
+    char_infos[char_code].left = face->glyph->bitmap_left;
+    char_infos[char_code].bitmap = malloc(char_infos[char_code].width * char_infos[char_code].height);
+    memcpy(char_infos[char_code].bitmap,
+            face->glyph->bitmap.buffer,
+            char_infos[char_code].width * char_infos[char_code].height);
+}
+
+static void generate_bytes(FILE * file, const uint8_t * bytes, int count)
+{
+    for (int i = 0; i < count; i++)
+    {
+        if (i % 8 == 0)
+        {
+            fprintf(file, "                ");
+        }
+        fprintf(file, "0x%02xu,", bytes[i]);
+        if ((i + 1) % 8 == 0)
+        {
+            fprintf(file, "\n");
+        }
+        else if (i < (count - 1))
+        {
+            fprintf(file, " ");
+        }
+    }
+    if (count % 8 != 0)
+    {
+        fprintf(file, "\n");
+    }
+}
+
+static void generate(const char * d_file_name)
+{
+    FILE * fh = fopen(d_file_name, "wb");
+    fprintf(fh, "module hulk.kfont;\n");
+    fprintf(fh, "struct CharInfo {\n");
+    fprintf(fh, "    uint width;\n");
+    fprintf(fh, "    uint height;\n");
+    fprintf(fh, "    int top;\n");
+    fprintf(fh, "    int left;\n");
+    fprintf(fh, "    const ubyte[] bitmap;\n");
+    fprintf(fh, "};\n");
+    fprintf(fh, "struct FontInfo {\n");
+    fprintf(fh, "    uint line_height;\n");
+    fprintf(fh, "    uint advance;\n");
+    fprintf(fh, "    int baseline_offset;\n");
+    fprintf(fh, "    const CharInfo[] chars;\n");
+    fprintf(fh, "};\n");
+    fprintf(fh, "__gshared const FontInfo kfont = {\n");
+    fprintf(fh, "    %du,\n", line_height);
+    fprintf(fh, "    %du,\n", max_advance);
+    fprintf(fh, "    %d,\n", baseline_offset);
+    fprintf(fh, "    [\n");
+    for (int i = 0; i < N_CHARS; i++)
+    {
+        fprintf(fh, "        CharInfo(\n");
+        fprintf(fh, "            %du,\n", char_infos[i].width);
+        fprintf(fh, "            %du,\n", char_infos[i].height);
+        fprintf(fh, "            %d,\n", char_infos[i].top);
+        fprintf(fh, "            %d,\n", char_infos[i].left);
+        if (char_infos[i].width > 0)
+        {
+            fprintf(fh, "            [\n");
+            generate_bytes(fh, char_infos[i].bitmap, char_infos[i].width * char_infos[i].height);
+            fprintf(fh, "            ]\n");
+        }
+        else
+        {
+            fprintf(fh, "            []\n");
+        }
+        fprintf(fh, "        ),\n");
+    }
+    fprintf(fh, "    ],\n");
+    fprintf(fh, "};\n");
+    fclose(fh);
+}
+
+int main(int argc, char * argv[])
+{
+    /* Expect: font file, size, out file */
+    if (argc != 4)
+    {
+        fprintf(stderr, "Incorrect arguments\n");
+        return 1;
+    }
+    const char * font_file = argv[1];
+    int size = atoi(argv[2]);
+    const char * out_file = argv[3];
+
+    FT_Library ft_library;
+    if (FT_Init_FreeType(&ft_library) != 0)
+    {
+        fprintf(stderr, "Could not initialize freetype\n");
+        return 2;
+    }
+
+    FT_Face face;
+    if (FT_New_Face(ft_library, font_file, 0, &face) != 0)
+    {
+        fprintf(stderr, "Could not open %s\n", font_file);
+        return 3;
+    }
+
+    FT_Set_Pixel_Sizes(face, 0, size);
+
+    for (int i = 0; i < N_CHARS; i++)
+    {
+        load_char(face, i);
+    }
+    line_height = round_up_26_6(face->size->metrics.height);
+    baseline_offset = (line_height - (max_top - min_bottom)) / 2 - min_bottom;
+
+    generate(out_file);
+
+    return 0;
+}

src/hello/console.d

@@ -0,0 +1,181 @@
+/**
+ * HELLO console support.
+ */
+module hello.console;
+
+import uefi;
+import hello.hello;
+import core.stdc.stdarg;
+
+struct console
+{
+    /**
+     * Format a hexadecimal value to a string.
+     *
+     * @param s String buffer.
+     * @param v Value to format.
+     * @param ptr If true, always output all 16 digits, and separate the upper and
+     *   lower halves with an underscore.
+     */
+    private static size_t format_hex(CHAR16 * s, ulong v, bool ptr)
+    {
+        string hex_chars = "0123456789ABCDEF";
+        bool print = ptr;
+        size_t si = 0u;
+        for (size_t i = 0u; i < 16u; i++)
+        {
+            if (ptr && (i == 8u))
+            {
+                s[si++] = '_';
+            }
+            ulong n = (v >> (60u - 4u * i)) & 0xFu;
+            if (n != 0u)
+            {
+                print = true;
+            }
+            if (print || (i == 15u))
+            {
+                s[si++] = hex_chars[n];
+            }
+        }
+        return si;
+    }
+
+    /**
+     * Format a decimal value to a string.
+     *
+     * @param s String buffer.
+     * @param v Value to format.
+     */
+    private static size_t format_dec(CHAR16 * s, ulong v)
+    {
+        string dec_chars = "0123456789";
+        bool print;
+        char[20] buf;
+        size_t buf_i;
+        while ((buf_i == 0u) || (v != 0u))
+        {
+            ulong n = v % 10u;
+            buf[buf_i++] = dec_chars[n];
+            v /= 10u;
+        }
+        for (size_t si = 0u; si < buf_i; si++)
+        {
+            s[si] = buf[buf_i - si - 1u];
+        }
+        return buf_i;
+    }
+
+    /**
+     * Write a string to the console.
+     *
+     * @param s Format string.
+     * @param args Variable arguments structure.
+     */
+    public static void write(string s, va_list args)
+    {
+        __gshared static CHAR16[256] s16;
+        size_t i = 0u;
+        bool escape = false;
+        foreach (char c; s)
+        {
+            if (escape)
+            {
+                if (c == '%')
+                {
+                    s16[i++] = '%';
+                }
+                else if (c == 'x')
+                {
+                    ulong v;
+                    va_arg(args, v);
+                    i += format_hex(&s16[i], v, false);
+                }
+                else if (c == 'p')
+                {
+                    ulong v;
+                    va_arg(args, v);
+                    i += format_hex(&s16[i], v, true);
+                }
+                else if (c == 'S')
+                {
+                    const(CHAR16) * s2;
+                    va_arg(args, s2);
+                    for (size_t s2_i = 0u; s2[s2_i] != 0; s2_i++)
+                    {
+                        s16[i++] = s2[s2_i];
+                    }
+                }
+                else if (c == 'u')
+                {
+                    ulong v;
+                    va_arg(args, v);
+                    i += format_dec(&s16[i], v);
+                }
+                else
+                {
+                    s16[i++] = c;
+                }
+                escape = false;
+            }
+            else if (c == '%')
+            {
+                escape = true;
+            }
+            else
+            {
+                s16[i++] = c;
+            }
+        }
+        s16[i++] = 0u;
+        st.ConOut.OutputString(st.ConOut, &s16[0]);
+    }
+
+    /**
+     * Write a string to the console.
+     *
+     * @param s Format string.
+     */
+    public static extern (C) void write(string s, ...)
+    {
+        va_list args;
+        va_start(args, s);
+        write(s, args);
+        va_end(args);
+    }
+
+    /**
+     * Write a string to the console.
+     *
+     * @param s Format string.
+     */
+    public static extern (C) void writeln(string s, ...)
+    {
+        va_list args;
+        va_start(args, s);
+        write(s, args);
+        write("\r\n", args);
+        va_end(args);
+    }
+
+    /**
+     * Write a message to press any key and wait for a key to be pressed.
+     */
+    public static void wait_key()
+    {
+        writeln("Press any key...");
+        st.ConIn.Reset(st.ConIn, FALSE);
+        EFI_INPUT_KEY key;
+        while (st.ConIn.ReadKeyStroke(st.ConIn, &key) == EFI_NOT_READY)
+        {
+        }
+    }
+
+    /**
+     * Clear the console.
+     */
+    public static void clear()
+    {
+        st.ConOut.ClearScreen(st.ConOut);
+    }
+}

src/hello/hello.d

@@ -0,0 +1,562 @@
+/**
+ * HELLO, the HOS EFI Lightweight LOader.
+ */
+module hello.hello;
+
+import uefi;
+import hello.console;
+import hulk.bootinfo;
+import hulk.header;
+import hulk.pagetable;
+import hulk.cpu;
+import hulk.memory;
+import ldc.llvmasm;
+
+__gshared EFI_SYSTEM_TABLE * st;
+/** HULK binary start address, 4KB-aligned. */
+extern extern(C) __gshared ubyte _hulk_bin_start;
+/** HULK binary end address, 4KB-aligned. */
+extern extern(C) __gshared ubyte _hulk_bin_end;
+private align(4096) __gshared ubyte[1024 * 1024] scratch_buffer;
+/** Index to the memory map region being used to allocate page tables. */
+private __gshared size_t memory_map_page_table_alloc_index;
+
+private HulkHeader * hulk_header()
+{
+    return cast(HulkHeader *)&_hulk_bin_start;
+}
+
+private BootInfo * bootinfo()
+{
+    return &hulk_header().bootinfo;
+}
+
+private ulong hulk_bin_phys()
+{
+    return cast(ulong)&_hulk_bin_start;
+}
+
+private ulong hulk_bin_size()
+{
+    return cast(ulong)&_hulk_bin_end - cast(ulong)&_hulk_bin_start;
+}
+
+private ulong hulk_bss_size()
+{
+    return cast(ulong)hulk_header().hulk_bss_size;
+}
+
+private ulong hulk_stack_size()
+{
+    return hulk_header().stack_size;
+}
+
+private ulong hulk_virt_base_address()
+{
+    return hulk_header().virt_base;
+}
+
+private ulong hulk_virt_stack_top()
+{
+    return hulk_header().virt_stack_top;
+}
+
+private ulong hulk_virt_framebuffer_address()
+{
+    return hulk_header().virt_fb_buffer;
+}
+
+/**
+ * Detect if we're running in QEMU.
+ */
+private bool in_qemu()
+{
+    ulong * firmware_vendor = cast(ulong *) st.FirmwareVendor;
+    ulong fv1 = firmware_vendor[0];
+    return fv1 ==
+        ((cast(ulong)'E') |
+         (cast(ulong)'D' << 16) |
+         (cast(ulong)'K' << 32) |
+         (cast(ulong)' ' << 48));
+}
+
+/**
+ * Set a graphics mode.
+ */
+private bool set_graphics_mode()
+{
+    uint max_horizontal_resolution = in_qemu() ? 1920u : 0xFFFFFFFFu;
+    UINTN buffer_size = scratch_buffer.sizeof;
+    EFI_GUID gop_guid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
+    EFI_HANDLE * handles = cast(EFI_HANDLE *)&scratch_buffer[0];
+    EFI_STATUS status = st.BootServices.LocateHandle(ByProtocol,
+            &gop_guid, null, &buffer_size, handles);
+    if (status != EFI_SUCCESS)
+    {
+        console.writeln("LocateHandle: error %x", status);
+        return false;
+    }
+    EFI_HANDLE gop_handle = handles[0];
+    EFI_HANDLE gop_interface;
+    status = st.BootServices.HandleProtocol(gop_handle,
+            &gop_guid, &gop_interface);
+    if (status != EFI_SUCCESS)
+    {
+        console.writeln("HandleProtocol: error %x", status);
+        return false;
+    }
+    if (gop_interface == null)
+    {
+        console.writeln("null interface from HandleProtocol");
+        return false;
+    }
+    EFI_GRAPHICS_OUTPUT_PROTOCOL * gop = cast(EFI_GRAPHICS_OUTPUT_PROTOCOL *)gop_interface;
+    UINTN info_size;
+    EFI_GRAPHICS_OUTPUT_MODE_INFORMATION * info;
+    uint best_width;
+    uint best_mode_number;
+    for (uint mode_number = 0u;
+         (status = gop.QueryMode(gop, mode_number, &info_size, &info)) == EFI_SUCCESS;
+         mode_number++)
+    {
+        if ((info.HorizontalResolution > best_width) &&
+            (info.HorizontalResolution <= max_horizontal_resolution))
+        {
+            best_width = info.HorizontalResolution;
+            best_mode_number = mode_number;
+        }
+        st.BootServices.FreePool(info);
+    }
+    if ((status = gop.SetMode(gop, best_mode_number)) != EFI_SUCCESS)
+    {
+        console.writeln("SetMode: Error %x\n", status);
+        return false;
+    }
+    bootinfo().fb.buffer = cast(uint *)gop.Mode.FrameBufferBase;
+    bootinfo().fb.width = gop.Mode.Info.HorizontalResolution;
+    bootinfo().fb.height = gop.Mode.Info.VerticalResolution;
+    bootinfo().fb.stride = gop.Mode.Info.PixelsPerScanLine;
+    bootinfo().fb.format = gop.Mode.Info.PixelFormat;
+    return true;
+}
+
+/**
+ * Walk the EFI memory map and translate it to the HULK bootinfo format.
+ */
+private void get_memory_map(ulong * physical_address_limit, UINTN * memory_map_key)
+{
+    immutable static ubyte[] efi_to_hulk_memory_map_type = [
+        BootInfo.MemoryRegion.Type.Reserved, // EfiReservedMemoryType
+        BootInfo.MemoryRegion.Type.Bootloader, // EfiLoaderCode
+        BootInfo.MemoryRegion.Type.Bootloader, // EfiLoaderData
+        BootInfo.MemoryRegion.Type.Bootloader, // EfiBootServicesCode
+        BootInfo.MemoryRegion.Type.Bootloader, // EfiBootServicesData
+        BootInfo.MemoryRegion.Type.Reserved, // EfiRuntimeServicesCode
+        BootInfo.MemoryRegion.Type.Reserved, // EfiRuntimeServicesData
+        BootInfo.MemoryRegion.Type.Conventional, // EfiConventionalMemory
+        BootInfo.MemoryRegion.Type.Unusable, // EfiUnusableMemory
+        BootInfo.MemoryRegion.Type.ACPIReclaim, // EfiACPIReclaimMemory
+        BootInfo.MemoryRegion.Type.ACPINVS, // EfiACPIMemoryNVS
+        BootInfo.MemoryRegion.Type.MemoryMappedIO, // EfiMemoryMappedIO
+        BootInfo.MemoryRegion.Type.MemoryMappedIOPortSpace, // EfiMemoryMappedIOPortSpace
+        BootInfo.MemoryRegion.Type.PalCode, // EfiPalCode
+    ];
+    *physical_address_limit = 0u;
+    UINTN memory_map_size = scratch_buffer.sizeof;
+    UINTN descriptor_size;
+    UINT32 descriptor_version;
+    ubyte * scratch_base = cast(ubyte *)&scratch_buffer[0];
+    UINTN status = st.BootServices.GetMemoryMap(
+            &memory_map_size,
+            cast(EFI_MEMORY_DESCRIPTOR *)scratch_base,
+            memory_map_key,
+            &descriptor_size,
+            &descriptor_version);
+    if (status != EFI_SUCCESS)
+    {
+        console.writeln("GetMemoryMap: Error %x", status);
+        for (;;) {}
+    }
+    size_t n_entries = memory_map_size / descriptor_size;
+    size_t count;
+    bool found_bss;
+    bool found_stack;
+    bool found_fb_buffer1;
+    const(size_t) fb_size = (bootinfo().fb.stride * bootinfo().fb.height * 4u + PAGE_SIZE - 1u) & ~(PAGE_SIZE - 1u);
+    for (count = 0u; count < n_entries; count++)
+    {
+        if (count > bootinfo().memory_map.length)
+        {
+            console.writeln("Memory map too large");
+            for (;;) {}
+        }
+        EFI_MEMORY_DESCRIPTOR * descriptor = cast(EFI_MEMORY_DESCRIPTOR *)&scratch_base[count * descriptor_size];
+        ulong end_address = descriptor.PhysicalStart + descriptor.NumberOfPages * 4096u;
+        if ((end_address > *physical_address_limit) &&
+            ((descriptor.Type == EfiLoaderCode) ||
+             (descriptor.Type == EfiLoaderData) ||
+             (descriptor.Type == EfiBootServicesCode) ||
+             (descriptor.Type == EfiBootServicesData) ||
+             (descriptor.Type == EfiRuntimeServicesCode) ||
+             (descriptor.Type == EfiRuntimeServicesData) ||
+             (descriptor.Type == EfiConventionalMemory)))
+        {
+            *physical_address_limit = end_address;
+        }
+        if (descriptor.Type >= efi_to_hulk_memory_map_type.length)
+        {
+            continue;
+        }
+        bootinfo().memory_map[count].base = descriptor.PhysicalStart;
+        bootinfo().memory_map[count].size = descriptor.NumberOfPages * 4096u;
+        bootinfo().memory_map[count].type = efi_to_hulk_memory_map_type[descriptor.Type];
+        if ((!found_bss) &&
+            (descriptor.Type == EfiConventionalMemory) &&
+            (bootinfo().memory_map[count].size >= hulk_bss_size()))
+        {
+            bootinfo().bss_phys = bootinfo().memory_map[count].base;
+            bootinfo().memory_map[count].base += hulk_bss_size();
+            bootinfo().memory_map[count].size -= hulk_bss_size();
+            found_bss = true;
+        }
+        if ((!found_stack) &&
+            (descriptor.Type == EfiConventionalMemory) &&
+            (bootinfo().memory_map[count].size >= hulk_stack_size()))
+        {
+            bootinfo().stack_phys = bootinfo().memory_map[count].base;
+            bootinfo().memory_map[count].base += hulk_stack_size();
+            bootinfo().memory_map[count].size -= hulk_stack_size();
+            found_stack = true;
+        }
+        if ((!found_fb_buffer1) &&
+            (descriptor.Type == EfiConventionalMemory) &&
+            (bootinfo().memory_map[count].size >= fb_size))
+        {
+            bootinfo().fb_buffer1_phys = bootinfo().memory_map[count].base;
+            bootinfo().memory_map[count].base += fb_size;
+            bootinfo().memory_map[count].size -= fb_size;
+            found_fb_buffer1 = true;
+        }
+    }
+    bootinfo().memory_map_count = count;
+    if ((!found_bss) || (!found_stack) || (!found_fb_buffer1))
+    {
+        for (;;) {}
+    }
+}
+
+private void * alloc_pt_page()
+{
+    BootInfo.MemoryRegion * regions = &bootinfo().memory_map[0];
+    for (;;)
+    {
+        BootInfo.MemoryRegion * region = &bootinfo().memory_map[memory_map_page_table_alloc_index];
+        if ((region.type == BootInfo.MemoryRegion.Type.Conventional) && (region.size >= PAGE_SIZE))
+        {
+            void * addr = cast(void *)region.base;
+            region.base += PAGE_SIZE;
+            region.size -= PAGE_SIZE;
+            return addr;
+        }
+        memory_map_page_table_alloc_index++;
+        if (memory_map_page_table_alloc_index >= bootinfo().memory_map_count)
+        {
+            return null;
+        }
+    }
+}
+
+/**
+ * Allocate a new page table.
+ */
+private PageTable * new_page_table()
+{
+    PageTable * pt = cast(PageTable *)alloc_pt_page();
+    if (pt == null)
+    {
+        return null;
+    }
+    memset64(pt, 0u, 512);
+    return pt;
+}
+
+/**
+ * Map a virtual address to a physical address using 4KB pages.
+ *
+ * @param source_page Source page address.
+ * @param dest_page Destination page address.
+ * @param pt_base Page table base address.
+ */
+private bool map4k(ulong source_page, ulong dest_page, PageTable * pt_base)
+{
+    PageTable * pt = pt_base;
+    for (size_t level = 0; level < 4u; level++)
+    {
+        PageTableEntry * ppte = pt.entry(source_page, level);
+        PageTableEntry pte = *ppte;
+        if (pte.present)
+        {
+            pt = pte.follow();
+        }
+        else
+        {
+            PageTable * next_pt;
+            ulong addr;
+            if (level < 3u)
+            {
+                next_pt = new_page_table();
+                if (next_pt == null)
+                {
+                    return false;
+                }
+                addr = cast(ulong)next_pt;
+            }
+            else
+            {
+                addr = dest_page;
+            }
+            *ppte = PageTableEntry(addr, PT_WRITABLE | PT_PRESENT);
+            pt = next_pt;
+        }
+    }
+    return true;
+}
+
+/**
+ * Map a virtual region to a physical region using 4KB pages.
+ *
+ * @param source Source address.
+ * @param dest Destination address.
+ * @param size Region size.
+ * @param pt_base Page table base address.
+ */
+private bool map4kregion(ulong source, ulong dest, size_t size, PageTable * pt_base)
+{
+    ulong end = source + size;
+    while (source < end)
+    {
+        if (!map4k(source, dest, pt_base))
+        {
+            return false;
+        }
+        source += 4096u;
+        dest += 4096u;
+    }
+    return true;
+}
+
+/**
+ * Map a virtual address to a physical address using 2MB pages.
+ *
+ * @param source_page Source page address.
+ * @param dest_page Destination page address.
+ * @param pt_base Page table base address.
+ */
+private bool map2m(ulong source_page, ulong dest_page, PageTable * pt_base)
+{
+    PageTable * pt = pt_base;
+    for (size_t level = 0; level < 3u; level++)
+    {
+        PageTableEntry * ppte = pt.entry(source_page, level);
+        PageTableEntry pte = *ppte;
+        if (pte.present)
+        {
+            pt = pte.follow();
+        }
+        else
+        {
+            PageTable * next_pt;
+            if (level < 2u)
+            {
+                next_pt = new_page_table();
+                if (next_pt == null)
+                {
+                    return false;
+                }
+                *ppte = PageTableEntry(next_pt, PT_WRITABLE | PT_PRESENT);
+            }
+            else
+            {
+                *ppte = PageTableEntry(dest_page, PT_HUGE_PAGE | PT_WRITABLE | PT_PRESENT);
+            }
+            pt = next_pt;
+        }
+    }
+    return true;
+}
+
+/**
+ * Map HULK virtual addresses to physical kernel location.
+ *
+ * @param pt_base Page table base address.
+ */
+private bool map_hulk(PageTable * pt_base)
+{
+    /* Map HULK bin region. */
+    ulong virt = hulk_virt_base_address();
+    if (!map4kregion(virt, hulk_bin_phys(), hulk_bin_size(), pt_base))
+    {
+        return false;
+    }
+    /* Map HULK bss region. */
+    virt += hulk_bin_size();
+    if (!map4kregion(virt, bootinfo().bss_phys, hulk_bss_size(), pt_base))
+    {
+        return false;
+    }
+    /* Map HULK stack. */
+    virt = hulk_virt_stack_top() - hulk_stack_size();
+    if (!map4kregion(virt, bootinfo().stack_phys, hulk_stack_size(), pt_base))
+    {
+        return false;
+    }
+    return true;
+}
+
+/**
+ * Build page tables in preparation to jump to HULK.
+ *
+ * @param physical_address_limit Maximum physical address to identity map.
+ */
+private bool build_page_tables(ulong physical_address_limit)
+{
+    PageTable * pt_base = new_page_table();
+    if (pt_base == null)
+    {
+        return false;
+    }
+    /* Map physical RAM. */
+    for (size_t addr = 0u; addr < physical_address_limit; addr += (2u * 1024u * 1024u))
+    {
+        if (!map2m(addr, addr, pt_base))
+        {
+            return false;
+        }
+    }
+    /* Map any memory regions that are outside physical RAM. */
+    for (size_t i = 0u; i < bootinfo().memory_map_count; i++)
+    {
+        ulong addr = bootinfo().memory_map[i].base;
+        if (addr >= physical_address_limit)
+        {
+            if (!map4kregion(addr, addr, bootinfo().memory_map[i].size, pt_base))
+            {
+                return false;
+            }
+        }
+    }
+    /* Map graphics framebuffer. */
+    ulong framebuffer_size = bootinfo().fb.height * bootinfo().fb.stride * 4u;
+    ulong fb_phys = cast(ulong)bootinfo().fb.buffer;
+    ulong fb_virt = hulk_virt_framebuffer_address();
+    if (!map4kregion(fb_virt, fb_phys, framebuffer_size, pt_base))
+    {
+        return false;
+    }
+    /* Map HULK regions. */
+    if (!map_hulk(pt_base))
+    {
+        return false;
+    }
+    /* Switch to the new page table. */
+    write_cr3(cast(ulong)pt_base);
+    return true;
+}
+
+/**
+ * Jump to HULK entry point.
+ */
+private void jump_to_hulk()
+{
+    __asm(
+            "jmpq *$0",
+            "r,{rsp}",
+            hulk_header().entry, hulk_virt_stack_top());
+}
+
+/**
+ * Find the ACPI XSDT.
+ *
+ * @return Whether it was found.
+ */
+private bool find_acpi_xsdt()
+{
+    for (size_t i = 0u; i < st.NumberOfTableEntries; i++)
+    {
+        if ((st.ConfigurationTable[i].VendorGuid == EFI_ACPI_TABLE_GUID) ||
+            (st.ConfigurationTable[i].VendorGuid == ACPI_TABLE_GUID))
+        {
+            enum ulong rsdp_magic = 0x20525450_20445352u;
+            const(EFI_ACPI_2_0_ROOT_SYSTEM_DESCRIPTION_POINTER) * rdsp = cast(const(EFI_ACPI_2_0_ROOT_SYSTEM_DESCRIPTION_POINTER) *)st.ConfigurationTable[i].VendorTable;
+            if (rdsp.Signature == rsdp_magic)
+            {
+                if (rdsp.Revision >= EFI_ACPI_2_0_ROOT_SYSTEM_DESCRIPTION_POINTER_REVISION)
+                {
+                    bootinfo().acpi_xsdt_phys = rdsp.XsdtAddress;
+                    return true;
+                }
+            }
+        }
+    }
+    return false;
+}
+
+/**
+ * EFI application entry point.
+ *
+ * @param image_handle EFI application handle.
+ * @param st Pointer to EFI system table.
+ */
+extern (C) EFI_STATUS efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE * st)
+{
+    .st = st;
+
+    console.clear();
+
+    console.writeln("Welcome to HELLO, HOS EFI Lightweight LOader, v0.1.0");
+    console.writeln("Firmware vendor: '%S', version: 0x%x", st.FirmwareVendor, st.FirmwareVendor);
+
+    if (!find_acpi_xsdt())
+    {
+        console.writeln("Error: Could not locate ACPI XSDT");
+        console.wait_key();
+        return EFI_SUCCESS;
+    }
+
+    if (!set_graphics_mode())
+    {
+        console.wait_key();
+        return EFI_SUCCESS;
+    }
+
+    ulong physical_address_limit;
+    UINTN memory_map_key;
+    for (;;)
+    {
+        get_memory_map(&physical_address_limit, &memory_map_key);
+
+        EFI_STATUS status = st.BootServices.ExitBootServices(image_handle, memory_map_key);
+        if (status == EFI_INVALID_PARAMETER)
+        {
+            continue;
+        }
+        if (status == EFI_SUCCESS)
+        {
+            break;
+        }
+        console.writeln("ExitBootServices: Error %x", status);
+        console.wait_key();
+        return EFI_SUCCESS;
+    }
+
+    if (!build_page_tables(physical_address_limit))
+    {
+        return EFI_SUCCESS;
+    }
+
+    bootinfo().hulk_phys = hulk_bin_phys();
+
+    jump_to_hulk();
+
+    return EFI_SUCCESS;
+}

src/hulk/acpi.d

@@ -0,0 +1,102 @@
+/**
+ * ACPI (Advanced Configuration and Power Interface) functionality.
+ */
+module hulk.acpi;
+
+import hulk.hurl;
+import hulk.klog;
+import hulk.memory;
+
+struct acpi
+{
+    enum uint APIC_SIGNATURE = 0x43495041u;
+    enum uint XSDT_SIGNATURE = 0x54445358u;
+
+    static struct XsdtHeader
+    {
+        uint signature;
+        uint length;
+        ubyte revision;
+        ubyte checksum;
+        char[6] oemid;
+        ulong oemtableid;
+        uint oem_revision;
+        uint creator_id;
+        uint creator_revision;
+    }
+
+    static struct Xsdt
+    {
+        XsdtHeader header;
+        uint _pad;
+        ulong[0] tables;
+    }
+
+    static struct MadtHeader
+    {
+        uint signature;
+        uint length;
+        ubyte revision;
+        ubyte checksum;
+        char[6] oemid;
+        ulong oemtableid;
+        uint oem_revision;
+        uint creator_id;
+        uint creator_revision;
+        uint local_apic_address;
+        uint flags;
+    }
+
+    static struct MadtEntry
+    {
+        ubyte type;
+        ubyte length;
+    }
+
+    public static __gshared ulong apic_address;
+
+    public static void initialize(ulong acpi_xsdt_phys)
+    {
+        /* Map the XSDT header. */
+        hurl.identity_map_range(acpi_xsdt_phys, Xsdt.sizeof, 0u);
+        const(Xsdt) * xsdt = cast(const(Xsdt) *)acpi_xsdt_phys;
+        if (xsdt.header.signature != XSDT_SIGNATURE)
+        {
+            klog.writef("XSDT signature invalid\n");
+            return;
+        }
+        /* Map the entire XSDT. */
+        hurl.identity_map_range(acpi_xsdt_phys, xsdt.header.length, 0u);
+        size_t n_entries = (xsdt.header.length - xsdt.header.sizeof) / xsdt.tables[0].sizeof;
+        for (size_t i = 0u; i < n_entries; i++)
+        {
+            ulong address = xsdt.tables[i];
+            hurl.identity_map_range(address, 4u, 0u);
+            uint signature = *cast(const(uint) *)address;
+            if (signature == APIC_SIGNATURE)
+            {
+                parse_apic_table(address);
+            }
+        }
+    }
+
+    private static parse_apic_table(ulong address)
+    {
+        const(MadtHeader) * madt_header = cast(const(MadtHeader) *)address;
+        hurl.identity_map_range(address, madt_header.length, 0u);
+        apic_address = madt_header.local_apic_address;
+        klog.writefln("Found 32-bit APIC address: 0x%x", apic_address);
+        const(void) * madt_end = cast(const(void) *)(address + madt_header.length);
+        const(MadtEntry) * madt_entry = cast(const(MadtEntry) *)(address + 0x2Cu);
+        while (madt_entry < madt_end)
+        {
+            madt_entry = cast(const(MadtEntry) *)(cast(size_t)madt_entry + madt_entry.length);
+            if (madt_entry.type == 5u)
+            {
+                /* Found a 64-bit Local APIC Address Override entry. */
+                memcpy(cast(void *)&apic_address, cast(const(void) *)madt_entry + 4u, 8u);
+                klog.writefln("Found 64-bit APIC address: 0x%x", apic_address);
+            }
+        }
+    }
+}

src/hulk/apic.d

@@ -0,0 +1,104 @@
+/**
+ * APIC (Advanced Programmable Interrupt Controller) functionality.
+ */
+module hulk.apic;
+
+import hulk.klog;
+import hulk.hurl;
+import hulk.acpi;
+import hulk.idt;
+
+struct apic
+{
+    private enum uint PERIODIC_MODE = 0x2_0000u;
+
+    static struct ApicRegister
+    {
+        public uint value;
+        alias value this;
+
+        private ubyte[12] _padding;
+    }
+
+    static struct ApicRegisters
+    {
+        ApicRegister[2] _reserved0;
+        ApicRegister lapic_id;
+        ApicRegister lapic_version;
+        ApicRegister[4] _reserved1;
+        ApicRegister task_priority;
+        ApicRegister arbitration_priority;
+        ApicRegister processor_priority;
+        ApicRegister eoi;
+        ApicRegister remote_read;
+        ApicRegister logical_destination;
+        ApicRegister destination_format;
+        ApicRegister spurious_interrupt_vector;
+        ApicRegister[8] in_service;
+        ApicRegister[8] trigger_mode;
+        ApicRegister[8] interrupt_request;
+        ApicRegister error_status;
+        ApicRegister[6] _reserved2;
+        ApicRegister lvt_cmci;
+        ApicRegister[2] interrupt_command;
+        ApicRegister lvt_timer;
+        ApicRegister lvt_thermal_sensor;
+        ApicRegister lvt_performance_monitoring_counters;
+        ApicRegister[2] lvt_lint;
+        ApicRegister lvt_error;
+        ApicRegister initial_count;
+        ApicRegister current_count;
+        ApicRegister[4] _reserved3;
+        ApicRegister divide_configuration;
+    }
+
+    static struct IoApicRegisters
+    {
+        ApicRegister address;
+        ApicRegister data;
+    }
+
+    private static __gshared ApicRegisters * apic_registers;
+    private static __gshared IoApicRegisters * io_apic_registers;
+
+    public static void initialize()
+    {
+        apic_registers = cast(ApicRegisters *)acpi.apic_address;
+        io_apic_registers = cast(IoApicRegisters *)0xFEC0_0000u;
+        hurl.map(cast(ulong)apic_registers, cast(ulong)apic_registers,
+                PT_WRITABLE | PT_WRITE_THROUGH | PT_DISABLE_CACHE | PT_NO_EXECUTE);
+        hurl.map(cast(ulong)io_apic_registers, cast(ulong)io_apic_registers,
+                PT_WRITABLE | PT_WRITE_THROUGH | PT_DISABLE_CACHE | PT_NO_EXECUTE);
+        klog.writefln("LAPIC ID: 0x%08x", apic_registers.lapic_id.value);
+        klog.writefln("LAPIC version: 0x%08x", apic_registers.lapic_version.value);
+        /* Enable local APIC to receive interrupts and set spurious interrupt
+         * vector to 0xFF. */
+        apic_registers.spurious_interrupt_vector.value = 0x1FFu;
+//        apic_registers.lvt_timer.value = idt.INT_LAPIC_TIMER | PERIODIC_MODE;
+        apic_registers.lvt_timer.value = idt.INT_LAPIC_TIMER;
+        apic_registers.lvt_lint[0].value = idt.INT_LAPIC_LINT0;
+        apic_registers.lvt_lint[1].value = idt.INT_LAPIC_LINT1;
+//        apic_registers.divide_configuration.value = 3u;
+        configure_io_apic_irq(8u, 0x48u);
+    }
+
+    private static void configure_io_apic_irq(size_t io_apic_irq, size_t interrupt_id)
+    {
+        ulong entry = interrupt_id;
+        io_apic_registers.address.value = cast(uint)(0x10u + io_apic_irq * 2u);
+        io_apic_registers.data.value = entry & 0xFFFF_FFFFu;
+        io_apic_registers.address.value = cast(uint)(0x10u + io_apic_irq * 2u + 1u);
+        io_apic_registers.data.value = entry >> 32u;
+    }
+
+    public static void eoi()
+    {
+        apic_registers.eoi.value = 0u;
+    }
+
+    public static void isr(ulong vector)
+    {
+        klog.writefln("APIC ISR 0x%x", vector);
+        eoi();
+    }
+}

src/hulk/bootinfo.d

@@ -0,0 +1,77 @@
+/**
+ * HULK boot information.
+ */
+module hulk.bootinfo;
+
+/**
+ * HULK boot information structure.
+ */
+struct BootInfo
+{
+    /**
+     * Framebuffer description structure.
+     */
+    struct Framebuffer
+    {
+        /** Framebuffer physical base address. */
+        uint * buffer;
+        /** Horizontal resolution. */
+        uint width;
+        /** Vertical resolution. */
+        uint height;
+        /** Number of pixels per scan line. */
+        uint stride;
+        /** Pixel format. */
+        uint format;
+    }
+
+    /**
+     * Memory map entry description structure.
+     */
+    struct MemoryRegion
+    {
+        enum Type
+        {
+            Reserved,
+            Bootloader,
+            Conventional,
+            Unusable,
+            ACPIReclaim,
+            ACPINVS,
+            MemoryMappedIO,
+            MemoryMappedIOPortSpace,
+            PalCode,
+        }
+
+        /** Base address of the memory region. */
+        ulong base;
+        /** Size in bytes of the memory region. */
+        size_t size;
+        /** Type of the memory region. */
+        ubyte type;
+    }
+
+    /* Framebuffer parameters. */
+    Framebuffer fb;
+
+    /* Memory map. */
+    MemoryRegion[1000] memory_map;
+
+    /* Number of memory map entries. */
+    size_t memory_map_count;
+
+    /* Physical address of HULK. */
+    ulong hulk_phys;
+
+    /* Physical address used for HULK bss section. */
+    ulong bss_phys;
+
+    /* Physical address of stack while jumping to HULK. */
+    ulong stack_phys;
+
+    /* Physical address of framebuffer buffer1. */
+    ulong fb_buffer1_phys;
+
+    /* Physical address of ACPI XSDT table. */
+    ulong acpi_xsdt_phys;
+}

src/hulk/console.d

@@ -0,0 +1,102 @@
+/**
+ * HULK Console functionality.
+ */
+module hulk.console;
+
+import hulk.fb;
+import hulk.kfont;
+
+struct console
+{
+    /** Console width in text columns. */
+    private static __gshared size_t m_width;
+
+    /** Console height in text rows. */
+    private static __gshared size_t m_height;
+
+    /** Current console cursor X position. */
+    private static __gshared size_t m_x;
+
+    /** Current console cursor Y position. */
+    private static __gshared size_t m_y;
+
+    /**
+     * Initialize the console.
+     */
+    public static void initialize()
+    {
+        m_width = fb.width / kfont.advance;
+        m_height = fb.height / kfont.line_height;
+    }
+
+    /**
+     * Clear the console.
+     */
+    public static void clear()
+    {
+        fb.clear();
+        m_x = 0u;
+        m_y = 0u;
+    }
+
+    /**
+     * Write a character to the console.
+     *
+     * @param ch Character to write.
+     */
+    public static void write(char ch)
+    {
+        if (ch == '\n')
+        {
+            m_x = 0u;
+            m_y++;
+        }
+        else
+        {
+            render_char(m_x, m_y, ch);
+            m_x++;
+            if (m_x == m_width)
+            {
+                m_x = 0u;
+                m_y++;
+            }
+        }
+        if (m_y == m_height)
+        {
+            m_y--;
+            fb.copy_rows_up(fb_y(m_height - 1u),
+                    (m_height - 1u) * kfont.line_height,
+                    kfont.line_height);
+            fb.rect(0u, fb_y(m_height - 1u), fb_x(m_width), kfont.line_height, 0u);
+        }
+    }
+
+    /**
+     * Render a character.
+     *
+     * @param x X position.
+     * @param y Y position.
+     * @param ch Character to render.
+     */
+    private static void render_char(size_t x, size_t y, char ch)
+    {
+        const(CharInfo) * ci = &kfont.chars[ch];
+        fb.blit_alpha_bitmap(fb_x(x) + ci.left, fb_y(y) + ci.top - ci.height, ci.bitmap, ci.width, ci.height);
+    }
+
+    /**
+     * Get the framebuffer X coordinate corresponding to the console X position.
+     */
+    private static size_t fb_x(size_t x)
+    {
+        return x * kfont.advance;
+    }
+
+    /**
+     * Get the framebuffer Y coordinate corresponding to the console Y position.
+     */
+    private static size_t fb_y(size_t y)
+    {
+        return fb.height - ((y + 1u) * kfont.line_height);
+    }
+}

src/hulk/cpu.d

@@ -0,0 +1,247 @@
+/**
+ * CPU functionality.
+ */
+module hulk.cpu;
+
+import ldc.llvmasm;
+
+/** CR0 bits. @{ */
+enum ulong CR0_PE = 0x1u;
+enum ulong CR0_MP = 0x2u;
+enum ulong CR0_EM = 0x4u;
+enum ulong CR0_TS = 0x8u;
+enum ulong CR0_ET = 0x10u;
+enum ulong CR0_NE = 0x20u;
+enum ulong CR0_WP = 0x1_0000u;
+enum ulong CR0_AM = 0x4_0000u;
+enum ulong CR0_NW = 0x2000_0000u;
+enum ulong CR0_CD = 0x4000_0000u;
+enum ulong CR0_PG = 0x8000_0000u;
+/** @} */
+
+/** CR4 bits. @{ */
+enum ulong CR4_VME = 0x1u;
+enum ulong CR4_PVI = 0x2u;
+enum ulong CR4_TSD = 0x4u;
+enum ulong CR4_DE = 0x8u;
+enum ulong CR4_PSE = 0x10u;
+enum ulong CR4_PAE = 0x20u;
+enum ulong CR4_MCE = 0x40u;
+enum ulong CR4_PGE = 0x80u;
+enum ulong CR4_PCE = 0x100u;
+enum ulong CR4_OSFXSR = 0x200u;
+enum ulong CR4_OSXMMEXCPT = 0x400u;
+enum ulong CR4_UMIP = 0x800u;
+enum ulong CR4_VMXE = 0x2000u;
+enum ulong CR4_SMXE = 0x4000u;
+enum ulong CR4_FSGSBASE = 0x1_0000u;
+enum ulong CR4_PCIDE = 0x2_0000u;
+enum ulong CR4_OSXSAVE = 0x4_0000u;
+enum ulong CR4_SMEP = 0x10_0000u;
+enum ulong CR4_SMAP = 0x20_0000u;
+enum ulong CR4_PKE = 0x40_0000u;
+enum ulong CR4_CET = 0x80_0000u;
+enum ulong CR4_PKS = 0x100_0000u;
+/** @} */
+
+/** XCR0 bits. @{ */
+enum ulong XCR0_X87 = 0x1u;
+enum ulong XCR0_SSE = 0x2u;
+enum ulong XCR0_AVX = 0x4u;
+enum ulong XCR0_BNDREG = 0x8u;
+enum ulong XCR0_BNDSCR = 0x10u;
+enum ulong XCR0_OPMASK = 0x20u;
+enum ulong XCR0_ZMM_HI256 = 0x40u;
+enum ulong XCR0_HI16_ZMM = 0x80u;
+enum ulong XCR0_PKRU = 0x100u;
+/** @} */
+
+/** MSR register numbers. @{ */
+enum uint MSR_EFER = 0xC000_0080u;
+/** @} */
+
+/** EFER flags. @{ */
+enum uint EFER_SCE = 0x1u;
+enum uint EFER_LME = 0x100u;
+enum uint EFER_LMA = 0x400u;
+enum uint EFER_NXE = 0x800u;
+enum uint EFER_SVME = 0x1000u;
+enum uint EFER_LMSLE = 0x2000u;
+enum uint EFER_FFXSR = 0x4000u;
+enum uint EFER_TCE = 0x8000u;
+/** @} */
+
+/** CPUID 1 bits. @{ */
+enum uint CPUID_1_EDX_FPU = 0x1u;
+enum uint CPUID_1_EDX_VME = 0x2u;
+enum uint CPUID_1_EDX_DE = 0x4u;
+enum uint CPUID_1_EDX_PSE = 0x8u;
+enum uint CPUID_1_EDX_TSC = 0x10u;
+enum uint CPUID_1_EDX_MSR = 0x20u;
+enum uint CPUID_1_EDX_PAE = 0x40u;
+enum uint CPUID_1_EDX_MCE = 0x80u;
+enum uint CPUID_1_EDX_CX8 = 0x100u;
+enum uint CPUID_1_EDX_APIC = 0x200u;
+enum uint CPUID_1_EDX_SEP = 0x800u;
+enum uint CPUID_1_EDX_MTRR = 0x1000u;
+enum uint CPUID_1_EDX_PGE = 0x2000u;
+enum uint CPUID_1_EDX_MCA = 0x4000u;
+enum uint CPUID_1_EDX_CMOV = 0x8000u;
+enum uint CPUID_1_EDX_PAT = 0x1_0000u;
+enum uint CPUID_1_EDX_PSE36 = 0x2_0000u;
+enum uint CPUID_1_EDX_PSN = 0x4_0000u;
+enum uint CPUID_1_EDX_CLFSH = 0x8_0000u;
+enum uint CPUID_1_EDX_DS = 0x20_0000u;
+enum uint CPUID_1_EDX_ACPI = 0x40_0000u;
+enum uint CPUID_1_EDX_MMX = 0x80_0000u;
+enum uint CPUID_1_EDX_FXSR = 0x100_0000u;
+enum uint CPUID_1_EDX_SSE = 0x200_0000u;
+enum uint CPUID_1_EDX_SSE2 = 0x400_0000u;
+enum uint CPUID_1_EDX_SS = 0x800_0000u;
+enum uint CPUID_1_EDX_HTT = 0x1000_0000u;
+enum uint CPUID_1_EDX_TM = 0x2000_0000u;
+enum uint CPUID_1_EDX_IA64 = 0x4000_0000u;
+enum uint CPUID_1_EDX_PBE = 0x8000_0000u;
+enum uint CPUID_1_ECX_SSE3 = 0x1u;
+enum uint CPUID_1_ECX_PCLMULQDQ = 0x2u;
+enum uint CPUID_1_ECX_DTES64 = 0x4u;
+enum uint CPUID_1_ECX_MONITOR = 0x8u;
+enum uint CPUID_1_ECX_DSCPL = 0x10u;
+enum uint CPUID_1_ECX_VMX = 0x20u;
+enum uint CPUID_1_ECX_SMX = 0x40u;
+enum uint CPUID_1_ECX_EST = 0x80u;
+enum uint CPUID_1_ECX_TM2 = 0x100u;
+enum uint CPUID_1_ECX_SSSE3 = 0x200u;
+enum uint CPUID_1_ECX_CNXTID = 0x400u;
+enum uint CPUID_1_ECX_SDBG = 0x800u;
+enum uint CPUID_1_ECX_FMA = 0x1000u;
+enum uint CPUID_1_ECX_CX16 = 0x2000u;
+enum uint CPUID_1_ECX_XTPR = 0x4000u;
+enum uint CPUID_1_ECX_PDCM = 0x8000u;
+enum uint CPUID_1_ECX_PCID = 0x2_0000u;
+enum uint CPUID_1_ECX_DCA = 0x4_0000u;
+enum uint CPUID_1_ECX_SSE41 = 0x8_0000u;
+enum uint CPUID_1_ECX_SSE42 = 0x10_0000u;
+enum uint CPUID_1_ECX_X2APIC = 0x20_0000u;
+enum uint CPUID_1_ECX_MOVBE = 0x40_0000u;
+enum uint CPUID_1_ECX_POPCNT = 0x80_0000u;
+enum uint CPUID_1_ECX_TSCDEADLINE = 0x100_0000u;
+enum uint CPUID_1_ECX_AES = 0x200_0000u;
+enum uint CPUID_1_ECX_XSAVE = 0x400_0000u;
+enum uint CPUID_1_ECX_OSXSAVE = 0x800_0000u;
+enum uint CPUID_1_ECX_AVX = 0x1000_0000u;
+enum uint CPUID_1_ECX_F16C = 0x2000_0000u;
+enum uint CPUID_1_ECX_RDRND = 0x4000_0000u;
+enum uint CPUID_1_ECX_HYPERVISOR = 0x8000_0000u;
+/** @} */
+
+void cli()
+{
+    __asm("cli", "");
+}
+
+void sti()
+{
+    __asm("sti", "");
+}
+
+void hlt()
+{
+    __asm("hlt", "");
+}
+
+ulong read_cr0()
+{
+    return __asm!ulong("mov %cr0, %rax", "={rax}");
+}
+
+void write_cr0(ulong v)
+{
+    __asm("mov $0, %cr0", "r", v);
+}
+
+ulong read_cr2()
+{
+    return __asm!ulong("mov %cr2, %rax", "={rax}");
+}
+
+ulong read_cr3()
+{
+    return __asm!ulong("mov %cr3, %rax", "={rax}");
+}
+
+void write_cr3(ulong v)
+{
+    __asm("mov $0, %cr3", "r", v);
+}
+
+ulong read_cr4()
+{
+    return __asm!ulong("mov %cr4, %rax", "={rax}");
+}
+
+void write_cr4(ulong v)
+{
+    __asm("mov $0, %cr4", "r", v);
+}
+
+ulong rdmsr(uint msr)
+{
+    return __asm!ulong(`
+            rdmsr
+            shl $$32, %rdx
+            or %rdx, %rax`, "={rax},{ecx},~{rdx}", msr);
+}
+
+void wrmsr(uint msr, ulong value)
+{
+    __asm(`wrmsr`, "{ecx},{edx},{eax}", msr, value >> 32u, value);
+}
+
+ulong xgetbv(uint xcr)
+{
+    return __asm!ulong(`
+            xgetbv
+            shl $$32, %rdx
+            or %rdx, %rax`, "={rax},{ecx},~{rdx}", xcr);
+}
+
+void xsetbv(uint xcr, ulong value)
+{
+    __asm(`xsetbv`, "{ecx},{edx},{eax}", xcr, value >> 32u, value);
+}
+
+ubyte in8(ushort ioaddr)
+{
+    return __asm!ubyte("inb %dx, %al", "={al},{dx}", ioaddr);
+}
+
+ushort in16(ushort ioaddr)
+{
+    return __asm!ushort("inw %dx, %ax", "={ax},{dx}", ioaddr);
+}
+
+ulong in32(ushort ioaddr)
+{
+    return __asm!ulong("inl %dx, %eax", "={eax},{dx}", ioaddr);
+}
+
+void out8(ushort ioaddr, ubyte v)
+{
+    __asm("outb %al, %dx", "{dx},{al}", ioaddr, v);
+}
+
+void out16(ushort ioaddr, ushort v)
+{
+    __asm("outw %ax, %dx", "{dx},{ax}", ioaddr, v);
+}
+
+void out32(ushort ioaddr, ulong v)
+{
+    __asm("outl %eax, %dx", "{dx},{eax}", ioaddr, v);
+}
+
+void cpuid1(uint * ebx, uint * ecx, uint * edx)
+{
+    __asm("cpuid", "=*{ebx},=*{ecx},=*{edx},{eax}", ebx, ecx, edx, 1u);
+}

src/hulk/fb.d

@@ -0,0 +1,292 @@
+/**
+ * HULK Framebuffer support.
+ */
+module hulk.fb;
+
+import hulk.memory;
+import hulk.kfont;
+
+/**
+ * Represent a graphical frame buffer.
+ *
+ * TODO: Handle other pixel formats. Currently only BGRx is supported.
+ */
+struct fb
+{
+    /** Device frame buffer base address. */
+    private __gshared static uint * m_device_buffer;
+
+    /** Frame buffer 1 base address. */
+    private __gshared static uint * m_buffer1;
+
+    /** Frame buffer width. */
+    private __gshared static uint m_width;
+
+    /** Frame buffer height. */
+    private __gshared static uint m_height;
+
+    /** Frame buffer stride. */
+    private __gshared static uint m_stride;
+
+    /** Number of pixels in the frame buffer (whether visible or not). */
+    private __gshared static uint m_buffer_size;
+
+    /**
+     * Get the framebuffer width.
+     */
+    public static @property uint width()
+    {
+        return m_width;
+    }
+
+    /**
+     * Get the framebuffer height.
+     */
+    public static @property uint height()
+    {
+        return m_height;
+    }
+
+    /**
+     * Initialize a frame buffer.
+     *
+     * @param device_buffer Device frame buffer base address.
+     * @param buffer1 Frame buffer 1 base address.
+     * @param width Frame buffer width.
+     * @param height Frame buffer height.
+     * @param stride Frame buffer stride.
+     */
+    static void initialize(uint * device_buffer, uint * buffer1, uint width, uint height, uint stride)
+    {
+        m_device_buffer = device_buffer;
+        m_buffer1 = buffer1;
+        m_width = width;
+        m_height = height;
+        m_stride = stride;
+        m_buffer_size = stride * height;
+    }
+
+    /**
+     * Clear the frame buffer to the given color.
+     *
+     * @param color Color to clear to.
+     */
+    static void clear(uint color = 0u)
+    {
+        memset32(m_buffer1, color, m_buffer_size);
+        memset32(m_device_buffer, color, m_buffer_size);
+    }
+
+    /**
+     * Draw a solid rectangle on the framebuffer.
+     *
+     * @param x X coordinate of left side of rectangle.
+     * @param y Y coordinate of bottom side of rectangle.
+     * @param width Width of rectangle.
+     * @param height Height of rectangle.
+     * @param color Color of rectangle.
+     */
+    static void rect(size_t x, size_t y, size_t width, size_t height, uint color)
+    {
+        for (size_t iy = 0u; iy < height; iy++)
+        {
+            size_t buffer_index = buffer_index(x, y);
+            memset32(&m_buffer1[buffer_index], color, width);
+            memset32(&m_device_buffer[buffer_index], color, width);
+            y++;
+        }
+    }
+
+    /**
+     * Draw a horizontal line.
+     *
+     * @param x X coordinate of left side of line.
+     * @param y Y coordinate of line.
+     * @param width Width of line.
+     * @param color Color of line.
+     */
+    static void hline(size_t x, size_t y, size_t width, uint color)
+    {
+        size_t buffer_index = buffer_index(x, y);
+        memset32(&m_buffer1[buffer_index], color, width);
+        memset32(&m_device_buffer[buffer_index], color, width);
+    }
+
+    /**
+     * Draw a vertical line.
+     *
+     * @param x X coordinate of line.
+     * @param y Y coordinate of bottom of line.
+     * @param height Height of line.
+     * @param color Color of line.
+     */
+    static void vline(size_t x, size_t y, size_t height, uint color)
+    {
+        size_t buffer_index = buffer_index(x, y);
+        for (size_t iy = 0u; iy < height; iy++)
+        {
+            m_buffer1[buffer_index] = color;
+            m_device_buffer[buffer_index] = color;
+            buffer_index -= m_stride;
+        }
+    }
+
+    /**
+     * Draw a character.
+     *
+     * @param x X coordinate of left side of character.
+     * @param y Y coordinate of bottom side of character.
+     * @param ch Character to draw.
+     * @param color Color of character.
+     */
+    static void character(int x, int y, char ch, uint color)
+    {
+        const(CharInfo) * ci = &kfont.chars[ch];
+        blend_alpha_bitmap(x + ci.left, y + kfont.baseline_offset + ci.top - ci.height, ci.bitmap, ci.width, ci.height, color);
+    }
+
+    /**
+     * Blend an 8-bit alpha bitmap to the framebuffer.
+     *
+     * @param x X coordinate of left side of target location.
+     * @param y Y coordinate of bottom side of target location.
+     * @param alpha_bitmap 8-bit alpha-channel bitmap.
+     * @param width Bitmap width.
+     * @param height Bitmap height.
+     * @param color Color to blend with alpha value.
+     */
+    static void blend_alpha_bitmap(size_t x, size_t y, const(ubyte) * alpha_bitmap,
+            size_t width, size_t height, uint color)
+    {
+        y += height - 1u;
+        size_t bitmap_index;
+        for (size_t iy = 0u; iy < height; iy++)
+        {
+            size_t row_buffer_index = buffer_index(x, y);
+            for (size_t ix = 0u; ix < width; ix++)
+            {
+                size_t buffer_index = row_buffer_index + ix;
+                ubyte alpha = alpha_bitmap[bitmap_index];
+                uint current_color = m_buffer1[buffer_index];
+                uint in_color_scaled = scale_color(color, alpha);
+                uint old_color_scaled = scale_color(current_color, 255u - alpha);
+                uint new_color = old_color_scaled + in_color_scaled;
+                m_buffer1[buffer_index] = new_color;
+                bitmap_index++;
+            }
+            memcpy32(&m_device_buffer[row_buffer_index], &m_buffer1[row_buffer_index], width);
+            y--;
+        }
+    }
+
+    /**
+     * Blend an 8-bit alpha bitmap to the framebuffer.
+     *
+     * @param x X coordinate of left side of target location.
+     * @param y Y coordinate of bottom side of target location.
+     * @param alpha_bitmap 8-bit alpha-channel bitmap.
+     * @param width Bitmap width.
+     * @param height Bitmap height.
+     * @param color Color to blend with alpha value.
+     */
+    static void blend_alpha_bitmap(size_t x, size_t y, const(ubyte)[] alpha_bitmap,
+            size_t width, size_t height, uint color)
+    {
+        blend_alpha_bitmap(x, y, alpha_bitmap.ptr, width, height, color);
+    }
+
+    /**
+     * Blit an 8-bit alpha bitmap to the framebuffer.
+     * The foreground will be white (based on the alpha value), and the
+     * background black.
+     *
+     * @param x X coordinate of left side of target location.
+     * @param y Y coordinate of bottom side of target location.
+     * @param alpha_bitmap 8-bit alpha-channel bitmap.
+     * @param width Bitmap width.
+     * @param height Bitmap height.
+     */
+    static void blit_alpha_bitmap(size_t x, size_t y, const(ubyte) * alpha_bitmap,
+            size_t width, size_t height)
+    {
+        y += height - 1u;
+        size_t bitmap_index;
+        for (size_t iy = 0u; iy < height; iy++)
+        {
+            size_t row_buffer_index = buffer_index(x, y);
+            for (size_t ix = 0u; ix < width; ix++)
+            {
+                size_t buffer_index = row_buffer_index + ix;
+                ubyte alpha = alpha_bitmap[bitmap_index];
+                m_buffer1[buffer_index] = (alpha << 16u) | (alpha << 8u) | alpha;
+                bitmap_index++;
+            }
+            memcpy32(&m_device_buffer[row_buffer_index], &m_buffer1[row_buffer_index], width);
+            y--;
+        }
+    }
+
+    /**
+     * Blit an 8-bit alpha bitmap to the framebuffer.
+     * The foreground will be white (based on the alpha value), and the
+     * background black.
+     *
+     * @param x X coordinate of left side of target location.
+     * @param y Y coordinate of bottom side of target location.
+     * @param alpha_bitmap 8-bit alpha-channel bitmap.
+     * @param width Bitmap width.
+     * @param height Bitmap height.
+     */
+    static void blit_alpha_bitmap(size_t x, size_t y, const(ubyte)[] alpha_bitmap,
+            size_t width, size_t height)
+    {
+        blit_alpha_bitmap(x, y, alpha_bitmap.ptr, width, height);
+    }
+
+    /**
+     * Copy framebuffer rows up in the framebuffer.
+     *
+     * @param y Y coordinate of bottom side of region to copy up.
+     * @param height Height of region to copy up.
+     * @param offset Number of rows to copy region up by.
+     */
+    static void copy_rows_up(size_t y, size_t height, size_t offset)
+    {
+        size_t dest_buffer_index = buffer_index(0u, y + height + offset - 1u);
+        size_t src_buffer_index = buffer_index(0u, y + height - 1u);
+        memcpy32(&m_buffer1[dest_buffer_index],
+                 &m_buffer1[src_buffer_index],
+                 (m_stride * height));
+        memcpy32(&m_device_buffer[dest_buffer_index],
+                &m_buffer1[dest_buffer_index],
+                (m_stride * height));
+    }
+
+    /**
+     * Scale a color value by an alpha amount.
+     *
+     * @param color Color value.
+     * @param alpha Alpha amount.
+     *
+     * @return Scaled color value.
+     */
+    private static uint scale_color(uint color, ubyte alpha)
+    {
+        return ((((color & 0xFFu) * alpha) >> 8u) & 0xFFu) |
+               ((((color & 0xFF00u) * alpha) >> 8u) & 0xFF00u) |
+               ((((color & 0xFF0000u) * alpha) >> 8u) & 0xFF0000u);
+    }
+
+    /**
+     * Return the buffer index for the given X and Y coordinates.
+     *
+     * @param x X coordinate from left side of framebuffer.
+     * @param y Y coordinate from bottom side of framebuffer.
+     *
+     * @return Buffer index for the given X and Y coordinates.
+     */
+    private static size_t buffer_index(size_t x, size_t y)
+    {
+        return (m_height - y - 1u) * m_stride + x;
+    }
+}

src/hulk/gdt.d

@@ -0,0 +1,58 @@
+/**
+ * GDT (Global Descriptor Table) functionality.
+ */
+module hulk.gdt;
+
+import ldc.llvmasm;
+
+struct gdt
+{
+    struct gdtr_t
+    {
+        ushort limit;
+        align(2) ulong offset;
+    }
+    static assert(gdtr_t.sizeof == 10u);
+
+    public enum size_t SELECTOR_NULL = 0x00u;
+    public enum size_t SELECTOR_KERNEL_CODE = 0x08u;
+    public enum size_t SELECTOR_KERNEL_DATA = 0x10u;
+    public enum size_t SELECTOR_COUNT = 3u;
+
+    static __gshared ulong[SELECTOR_COUNT] gdt;
+    static __gshared gdtr_t gdtr;
+
+    public static void initialize()
+    {
+        gdt[SELECTOR_KERNEL_CODE / ulong.sizeof] = 0x00_A_F_9A_000000_0000u;
+        gdt[SELECTOR_KERNEL_DATA / ulong.sizeof] = 0x00_C_F_92_000000_0000u;
+        gdtr.limit = gdt.sizeof - 1u;
+        gdtr.offset = cast(ulong)&gdt;
+        lgdt(&gdtr);
+        load_data_selectors(SELECTOR_KERNEL_DATA);
+        load_code_selector(SELECTOR_KERNEL_CODE);
+    }
+
+    private static void lgdt(gdtr_t * gdtr)
+    {
+        __asm("lgdt $0", "*m", gdtr);
+    }
+
+    private static void load_data_selectors(ulong selector)
+    {
+        __asm(`mov %ax, %ds
+               mov %ax, %es
+               mov %ax, %fs
+               mov %ax, %gs
+               mov %ax, %ss`, "{rax}", selector);
+    }
+
+    private static void load_code_selector(ulong selector)
+    {
+        __asm(`push %rax
+               movabs $$1f, %rax
+               push %rax
+               lretq
+               1:`, "{rax}", selector);
+    }
+}

src/hulk/header.d

@@ -0,0 +1,40 @@
+/**
+ * HULK image header.
+ */
+module hulk.header;
+
+import hulk.bootinfo;
+
+/**
+ * Header describing the HULK image.
+ */
+struct HulkHeader
+{
+    /**
+     * HULK BSS size.
+     *
+     * The OS loader must map memory to a zeroed range of this size.
+     *
+     * This value is really an integer, but is stored as a pointer because it
+     * is provided by the linker and LDC does not like us to cast it.
+     */
+    void * hulk_bss_size;
+
+    /** Entry point. */
+    void * entry;
+
+    /** Stack size. */
+    ulong stack_size;
+
+    /** Virtual base address. */
+    ulong virt_base;
+
+    /** Stack top virtual address. */
+    ulong virt_stack_top;
+
+    /** Framebuffer virtual address. */
+    ulong virt_fb_buffer;
+
+    /** HULK boot information. */
+    BootInfo bootinfo;
+}

src/hulk/hippo.d

@@ -0,0 +1,69 @@
+/**
+ * HIPPO, the HOS In-place Physical Page Organizer.
+ *
+ * HIPPO maintains a list of free physical pages "in place", meaning that the
+ * available page itself is used as the linked list entry so separate memory
+ * is not needed to keep track of the available pages.
+ */
+module hulk.hippo;
+
+struct hippo
+{
+    /**
+     * Linked list node entry for a physical page.
+     */
+    private static struct PhysicalPage
+    {
+        PhysicalPage * next;
+    }
+
+    /**
+     * Linked list of free physical pages.
+     */
+    private static __gshared PhysicalPage * free_pages;
+
+    /**
+     * Number of free physical pages.
+     */
+    private static __gshared size_t m_n_free_pages;
+
+    /**
+     * Free a physical page.
+     *
+     * @param phys Physical page address.
+     */
+    public static void free_page(T)(T phys)
+    {
+        PhysicalPage * pp = cast(PhysicalPage *)phys;
+        pp.next = free_pages;
+        free_pages = pp;
+        m_n_free_pages++;
+    }
+
+    /**
+     * Allocate a physical page.
+     *
+     * @return Page address, or null if no pages are available.
+     */
+    public static void * allocate_page()
+    {
+        PhysicalPage * pp;
+        if (free_pages != null)
+        {
+            pp = free_pages;
+            free_pages = free_pages.next;
+            m_n_free_pages--;
+        }
+        return cast(void *)pp;
+    }
+
+    /**
+     * Get the number of free pages.
+     *
+     * @return The number of free pages.
+     */
+    public @property size_t n_free_pages() const
+    {
+        return m_n_free_pages;
+    }
+}

src/hulk/hulk.d

@@ -0,0 +1,86 @@
+/**
+ * HULK, the HOS Ultra Light Kernel.
+ */
+module hulk.hulk;
+
+import hulk.header;
+import hulk.fb;
+import hulk.console;
+import hulk.memory;
+import ldc.attributes;
+import hulk.kfont;
+import hulk.klog;
+import hulk.hurl;
+import hulk.hippo;
+import hulk.pci;
+import hulk.gdt;
+import hulk.idt;
+import hulk.cpu;
+import ldc.llvmasm;
+import hulk.pic;
+import hulk.acpi;
+import hulk.apic;
+import hulk.rtc;
+import hulk.pit;
+
+extern extern(C) __gshared ubyte _hulk_bss_size;
+
+@(ldc.attributes.section(".hulk_header"))
+private __gshared HulkHeader hulk_header = {
+    &_hulk_bss_size, /* hulk_bss_size */
+    &hulk_start, /* entry */
+    16u * 1024u, /* stack_size */
+    HULK_VIRTUAL_BASE_ADDRESS, /* virt_base */
+    HULK_VIRTUAL_STACK_TOP_ADDRESS, /* virt_stack_top */
+    HULK_VIRTUAL_FRAMEBUFFER_ADDRESS, /* virt_fb_buffer */
+};
+
+private void initialize_cpu()
+{
+    /* Enable SSE. */
+    /* Turn off CR0.EM and turn on CR0.MP. */
+    write_cr0((read_cr0() & ~CR0_EM) | CR0_MP);
+    /* Set CR4.OSFXSR and CR4.OSXMMEXCPT. */
+    write_cr4(read_cr4() | CR4_OSFXSR | CR4_OSXMMEXCPT);
+
+    /* Enable OSXSAVE. */
+    write_cr4(read_cr4() | CR4_OSXSAVE);
+
+    /* Turn on NXE (no execute enable) flag in the EFER MSR. */
+    wrmsr(MSR_EFER, rdmsr(MSR_EFER) | EFER_NXE);
+}
+
+/**
+ * HULK entry point.
+ */
+void hulk_start()
+{
+    cli();
+    initialize_cpu();
+    gdt.initialize();
+    idt.initialize();
+    fb.initialize(cast(uint *)HULK_VIRTUAL_FRAMEBUFFER_ADDRESS,
+            cast(uint *)hulk_header.bootinfo.fb_buffer1_phys,
+            hulk_header.bootinfo.fb.width,
+            hulk_header.bootinfo.fb.height,
+            hulk_header.bootinfo.fb.stride);
+    console.initialize();
+    console.clear();
+    klog.initialize();
+
+    klog.writefln("Welcome to HULK, the HOS UltraLight Kernel!");
+
+    hurl.initialize(&hulk_header);
+    pci.initialize();
+    pic.initialize();
+    acpi.initialize(hulk_header.bootinfo.acpi_xsdt_phys);
+    apic.initialize();
+    rtc.initialize();
+    pit.initialize();
+    sti();
+
+    for (;;)
+    {
+        hlt();
+    }
+}

src/hulk/hulk.ld

@@ -0,0 +1,61 @@
+SECTIONS
+{
+    . = 0xFFFF800000000000;
+    _hulk_mem_start = .;
+    _hulk_header_start = .;
+
+    .hulk_header :
+    {
+        *(.hulk_header)
+    }
+
+    . = ALIGN(4K);
+    _hulk_header_end = .;
+    _hulk_text_start = .;
+
+    .text :
+    {
+        *(.text)
+    }
+
+    . = ALIGN(4K);
+    _hulk_text_end = .;
+    _hulk_rodata_start = .;
+
+    .rodata :
+    {
+        *(.rodata)
+    }
+
+    . = ALIGN(4K);
+
+    _hulk_rodata_end = .;
+    _hulk_data_start = .;
+
+    .data :
+    {
+        *(.data)
+    }
+
+    . = ALIGN(4K);
+    _hulk_data_end = .;
+    _hulk_binary_size = . - _hulk_mem_start;
+    _hulk_bss_start = .;
+
+    .bss :
+    {
+        *(COMMON)
+        *(.bss)
+    }
+
+    . = ALIGN(4K);
+    _hulk_bss_end = .;
+    _hulk_mem_end = .;
+
+    _hulk_header_size = _hulk_header_end - _hulk_header_start;
+    _hulk_text_size = _hulk_text_end - _hulk_text_start;
+    _hulk_rodata_size = _hulk_rodata_end - _hulk_rodata_start;
+    _hulk_data_size = _hulk_data_end - _hulk_data_start;
+    _hulk_bss_size = _hulk_bss_end - _hulk_bss_start;
+    _hulk_mem_size = _hulk_mem_end - _hulk_mem_start;
+}

src/hulk/hurl.d

@@ -0,0 +1,296 @@
+/**
+ * HURL, the HOS Unreal Region Locator.
+ *
+ * HURL provides virtual memory management for HULK.
+ */
+module hulk.hurl;
+
+public import hulk.pagetable;
+import hulk.cpu;
+import hulk.hippo;
+import hulk.memory;
+import hulk.klog;
+import hulk.bootinfo;
+import hulk.header;
+import hulk.linker_addresses;
+
+/** HULK virtual base address. */
+enum ulong HULK_VIRTUAL_BASE_ADDRESS = 0xFFFF_8000_0000_0000u;
+
+/** HULK virtual stack top address. */
+enum ulong HULK_VIRTUAL_STACK_TOP_ADDRESS = 0xFFFF_A000_0000_0000u;
+
+/** HULK virtual framebuffer address. */
+enum ulong HULK_VIRTUAL_FRAMEBUFFER_ADDRESS = 0xFFFF_A000_0000_0000u;
+
+struct hurl
+{
+    /**
+     * Pointer to the base page table.
+     */
+    private static __gshared PageTable * m_pt_base;
+
+    /**
+     * Build HULK page tables.
+     *
+     * @param physical_address_limit
+     *   Limit of physical memory.
+     */
+    private static void build_page_tables(HulkHeader * header, size_t physical_address_limit)
+    {
+        m_pt_base = allocate_pt();
+        /* Identity map all physical RAM. */
+        map_range(0u,
+                0u,
+                physical_address_limit,
+                PT_WRITABLE | PT_NO_EXECUTE);
+        ulong phys_address = header.bootinfo.hulk_phys;
+        ulong virt_address = HULK_VIRTUAL_BASE_ADDRESS;
+        /* Map HULK header region. */
+        map_range(virt_address,
+                phys_address,
+                LinkerAddresses.hulk_header_size,
+                PT_NO_EXECUTE);
+        phys_address += LinkerAddresses.hulk_header_size;
+        virt_address += LinkerAddresses.hulk_header_size;
+        /* Map HULK text region. */
+        map_range(virt_address,
+                phys_address,
+                LinkerAddresses.hulk_text_size,
+                0u);
+        phys_address += LinkerAddresses.hulk_text_size;
+        virt_address += LinkerAddresses.hulk_text_size;
+        /* Map HULK rodata region. */
+        map_range(virt_address,
+                phys_address,
+                LinkerAddresses.hulk_rodata_size,
+                PT_NO_EXECUTE);
+        phys_address += LinkerAddresses.hulk_rodata_size;
+        virt_address += LinkerAddresses.hulk_rodata_size;
+        /* Map HULK data region. */
+        map_range(virt_address,
+                phys_address,
+                LinkerAddresses.hulk_data_size,
+                PT_WRITABLE | PT_NO_EXECUTE);
+        virt_address += LinkerAddresses.hulk_data_size;
+        /* Map HULK BSS region. */
+        map_range(virt_address,
+                header.bootinfo.bss_phys,
+                LinkerAddresses.hulk_bss_size,
+                PT_WRITABLE | PT_NO_EXECUTE);
+        /* Map HULK stack. */
+        map_range(HULK_VIRTUAL_STACK_TOP_ADDRESS - header.stack_size,
+                header.bootinfo.stack_phys,
+                header.stack_size,
+                PT_WRITABLE | PT_NO_EXECUTE);
+        /* Map device framebuffer. */
+        map_range(HULK_VIRTUAL_FRAMEBUFFER_ADDRESS,
+                cast(ulong)header.bootinfo.fb.buffer,
+                header.bootinfo.fb.height * header.bootinfo.fb.stride * 4u,
+                PT_WRITABLE | PT_NO_EXECUTE);
+        /* Map framebuffer buffer1. */
+        map_range(cast(ulong)header.bootinfo.fb_buffer1_phys,
+                cast(ulong)header.bootinfo.fb_buffer1_phys,
+                header.bootinfo.fb.height * header.bootinfo.fb.stride * 4u,
+                PT_WRITABLE | PT_NO_EXECUTE);
+        write_cr3(cast(ulong)m_pt_base);
+    }
+
+    /**
+     * Reclaim the pages that were used for the bootloader page tables.
+     *
+     * @param pt
+     *   The page table to reclaim pages from.
+     * @param level
+     *   Page table level (internally used while recursing the page tables).
+     *
+     * @return Number of pages reclaimed.
+     */
+    private static size_t reclaim_bootloader_page_table_pages(PageTable * pt, size_t level = 0u)
+    {
+        map(pt, pt, PT_WRITABLE | PT_NO_EXECUTE);
+        size_t reclaimed_pages;
+        for (size_t i = 0u; i < PageTable.N_ENTRIES; i++)
+        {
+            PageTableEntry pte = (*pt)[i];
+            if (pte.present && (level < 2u) && !pte.huge)
+            {
+                /* For the first two levels of page tables, first
+                 * recurse and free pages from the lower level page
+                 * tables before reclaiming this entry. */
+                reclaimed_pages += reclaim_bootloader_page_table_pages(pte.follow(), level + 1u);
+            }
+        }
+        hippo.free_page(pt);
+        reclaimed_pages++;
+        return reclaimed_pages;
+    }
+
+    /**
+     * Initialize HURL.
+     *
+     * @param bootinfo HULK boot information structure.
+     */
+    public static void initialize(HulkHeader * header)
+    {
+        PageTable * bootloader_pt_base = cast(PageTable *)read_cr3();
+
+        /*
+         * Ok, what we do here is iterate through all of the memory map regions
+         * in the bootinfo memory_map array and mark each page that is not in
+         * use in a reserved range as available. Within the available memory
+         * regions, we have to watch out for the following items:
+         *   1) HULK binary (header + text + rodata + data)
+         *   2) Framebuffer
+         * In addition to these ranges, there are also pages for the following
+         * purposes that are not represented in the memory map from the
+         * bootloader:
+         *   3) HULK BSS
+         *   4) HULK stack
+         *   5) bootloader page table pages
+         *   6) framebuffer buffer1
+         */
+        size_t usable_memory;
+        size_t physical_address_limit;
+        const(size_t) fb_size = (header.bootinfo.fb.height * header.bootinfo.fb.stride * 4u + PAGE_SIZE - 1u) & ~(PAGE_SIZE - 1u);
+        ulong[2][2] reserved = [
+            [header.bootinfo.hulk_phys, LinkerAddresses.hulk_binary_size],
+            [cast(ulong)header.bootinfo.fb.buffer, fb_size],
+        ];
+        for (size_t ri = 0u; ri < reserved.length; ri++)
+        {
+            reserved[ri][1] += reserved[ri][0];
+        }
+        for (size_t bii = 0u; bii < header.bootinfo.memory_map_count; bii++)
+        {
+            if ((header.bootinfo.memory_map[bii].type == BootInfo.MemoryRegion.Type.Bootloader) ||
+                (header.bootinfo.memory_map[bii].type == BootInfo.MemoryRegion.Type.Conventional))
+            {
+                ulong phys = header.bootinfo.memory_map[bii].base;
+                ulong phys_end = phys + header.bootinfo.memory_map[bii].size;
+                if (phys_end > physical_address_limit)
+                {
+                    physical_address_limit = phys_end;
+                }
+                usable_memory += header.bootinfo.memory_map[bii].size;
+                while (phys < phys_end)
+                {
+                    bool is_reserved = false;
+                    for (size_t ri = 0u; ri < reserved.length; ri++)
+                    {
+                        if ((reserved[ri][0] <= phys) && (phys < reserved[ri][1]))
+                        {
+                            is_reserved = true;
+                            break;
+                        }
+                    }
+                    if (!is_reserved)
+                    {
+                        hippo.free_page(phys);
+                    }
+                    phys += PAGE_SIZE;
+                }
+            }
+        }
+
+        /*
+         * Now that we have available physical pages to allocate from, we can
+         * build new page tables to replace the bootloader page tables.
+         */
+        build_page_tables(header, physical_address_limit);
+
+        /*
+         * After we have switched to the newly constructed page tables, we can
+         * iterate through and free the bootloader page tables. They are most
+         * likely already mapped because we just identity mapped every page up
+         * to the physical_address_limit determined above. But just in case the
+         * bootloader used the last pages of RAM for the page table pages, we
+         * will make sure to map them as we traverse them.
+         */
+        size_t reclaimed_bootloader_page_table_memory = reclaim_bootloader_page_table_pages(bootloader_pt_base) << 10u;
+        usable_memory += reclaimed_bootloader_page_table_memory;
+
+        usable_memory += LinkerAddresses.hulk_bss_size;
+        usable_memory += header.stack_size;
+        usable_memory += fb_size;
+        klog.writefln("Usable memory: %uKB", usable_memory >> 10u);
+        klog.writefln("Kernel size: %uKB", (LinkerAddresses.hulk_binary_size + LinkerAddresses.hulk_bss_size + header.stack_size) >> 10u);
+    }
+
+    public static void map(T, U)(T virtual, U physical, ulong flags)
+    {
+        PageTable * pt = m_pt_base;
+        for (size_t level = 0; level < 4u; level++)
+        {
+            PageTableEntry * ppte = pt.entry(virtual, level);
+            if (level < 3u)
+            {
+                PageTableEntry pte = *ppte;
+                if (pte.present)
+                {
+                    pt = pte.follow();
+                }
+                else
+                {
+                    PageTable * next_pt = allocate_pt();
+                    *ppte = PageTableEntry(next_pt, PT_WRITABLE | PT_PRESENT);
+                    pt = next_pt;
+                }
+            }
+            else
+            {
+                *ppte = PageTableEntry(cast(ulong)physical, flags | PT_PRESENT);
+            }
+        }
+    }
+
+    public static void map_range(size_t virtual, size_t physical, size_t length, ulong flags)
+    {
+        size_t end = virtual + length;
+        while (virtual < end)
+        {
+            map(virtual, physical, flags);
+            virtual += PAGE_SIZE;
+            physical += PAGE_SIZE;
+        }
+    }
+
+    public static void identity_map_range(size_t address, size_t length, ulong flags)
+    {
+        size_t end = address + length;
+        for (size_t page = address & ~0xFFFu; page < end; page += PAGE_SIZE)
+        {
+            map(page, page, flags);
+        }
+    }
+
+    public static void debug_lookup(void * address)
+    {
+        klog.writefln("Debugging page table lookup of 0x%x", address);
+        PageTable * pt = m_pt_base;
+        for (size_t level = 0; level < 4u; level++)
+        {
+            PageTableEntry pte = *pt.entry(address, level);
+            klog.writefln("Level %u, index %u, entry = 0x%x", level, pt.index(address, level), pte);
+            if (pte.present)
+            {
+                pt = pte.follow();
+            }
+            else
+            {
+                break;
+            }
+            if (pte.huge)
+            {
+                break;
+            }
+        }
+    }
+
+    private static PageTable * allocate_pt()
+    {
+        PageTable * pt = cast(PageTable *)hippo.allocate_page();
+        memset64(pt, 0u, PAGE_SIZE / 8u);
+        return pt;
+    }
+}

src/hulk/idt.d

@@ -0,0 +1,128 @@
+/**
+ * IDT (Interrupt Descriptor Table) functionality.
+ */
+module hulk.idt;
+
+import hulk.gdt;
+import ldc.llvmasm;
+import hulk.fb;
+import hulk.console;
+import hulk.klog;
+import hulk.apic;
+import hulk.rtc;
+
+struct idt
+{
+    /* The I/O APIC is configured to map IRQ 0 to interrupt 64 (0x40). */
+    public static enum ulong INT_RTC = 0x48u; /* IRQ 8 */
+
+    public static enum ulong INT_LAPIC_TIMER = 0x70u;
+    public static enum ulong INT_LAPIC_LINT0 = 0x71u;
+    public static enum ulong INT_LAPIC_LINT1 = 0x72u;
+
+    struct idtr_t
+    {
+        ushort limit;
+        align(2) ulong offset;
+    }
+    static assert(idtr_t.sizeof == 10u);
+
+    alias descriptor_t = ulong[2];
+
+    static __gshared align(0x10) descriptor_t[256] idt;
+    static assert(idt.sizeof == (256u * 16u));
+    static __gshared idtr_t idtr;
+
+    public static void initialize()
+    {
+        set_isrs();
+        idtr.limit = idt.sizeof - 1u;
+        idtr.offset = cast(ulong)&idt;
+        lidt(&idtr);
+    }
+
+    private static void lidt(idtr_t * idtr)
+    {
+        __asm("lidt $0", "*m", idtr);
+    }
+
+    private static bool isr_has_error_code(size_t isr)
+    {
+        return (isr == 8) ||
+            ((10 <= isr) && (isr <= 14)) ||
+            (isr == 17) ||
+            (isr == 21) ||
+            (isr == 29) ||
+            (isr == 30);
+    }
+
+    private static bool isr_is_trap(size_t isr)
+    {
+        return (isr < 32u) && (isr != 2u);
+    }
+
+    private static void set_isrs()
+    {
+        ulong isr_address;
+        static foreach(isr; 0 .. 256)
+        {
+            mixin("isr_address = __asm!ulong(`
+                movabs $$1f, %rax
+                jmp 2f
+                1:
+                pushq %rdi
+                pushq %rsi
+                pushq %rax
+                mov $$", isr, ", %rdi
+                " ~ (isr_has_error_code(isr) ? "mov 0x18(%rsp), %rsi" : "") ~ "
+                movabs $$isr, %rax
+                callq *%rax
+                popq %rax
+                popq %rsi
+                popq %rdi
+                " ~ (isr_has_error_code(isr) ? "add $$8, %rsp" : "") ~ "
+                iretq
+                2:`, `={rax}`);");
+            mixin("set_descriptor(", isr, ", 0u, " ~
+                    (isr_is_trap(isr) ? "true" : "false") ~ ", isr_address);");
+        }
+    }
+
+    private static void set_descriptor(size_t index, ulong dpl, bool trap, ulong offset)
+    {
+        idt[index][0] =
+            0x0000_8E_00_0000_0000u |
+            ((offset & 0xFFFF_0000u) << 32u) |
+            (dpl << 45u) |
+            ((trap ? 1uL : 0uL) << 40u) |
+            (gdt.SELECTOR_KERNEL_CODE << 16u) |
+            (offset & 0xFFFFu);
+        idt[index][1] = offset >> 32u;
+    }
+}
+
+public extern(C) void isr(ulong vector, ulong arg)
+{
+    switch (vector)
+    {
+    case idt.INT_RTC:
+        rtc.isr();
+        break;
+
+    case idt.INT_LAPIC_TIMER:
+    case idt.INT_LAPIC_LINT0:
+    case idt.INT_LAPIC_LINT1:
+        apic.isr(vector);
+        break;
+
+    default:
+        console.clear();
+        fb.clear(0xFF8000u);
+        klog.writefln("ISR %u, 0x%x", vector, arg);
+        __asm("cli", "");
+        for (;;)
+        {
+            __asm("hlt", "");
+        }
+    }
+}

src/hulk/klog.d

@@ -0,0 +1,73 @@
+/**
+ * HULK Kernel Log buffer.
+ */
+module hulk.klog;
+
+import core.stdc.stdarg;
+import hulk.console;
+static import hulk.writef;
+
+struct klog
+{
+    /**
+     * Kernel buffer size log.
+     * 16 gives a kernel buffer size of 64KB.
+     */
+    private enum size_t KLOG_SIZE_LOG = 16u;
+
+    /** Kernel buffer size.  */
+    private enum size_t KLOG_SIZE = 1u << KLOG_SIZE_LOG;
+
+    /** Kernel log buffer. */
+    private static __gshared align(4096) ubyte[KLOG_SIZE] klog_buffer;
+
+    /** Write index in the kernel log buffer. */
+    private static __gshared size_t klog_index;
+
+    /**
+     * Initialize the klog module.
+     */
+    public static void initialize()
+    {
+    }
+
+    /**
+     * Write a formatted string to the kernel log.
+     *
+     * @param s Format string.
+     * @param args Variable arguments structure.
+     */
+    public static void writef(string s, va_list args)
+    {
+        hulk.writef.writef(s, args, function void(ubyte ch) {
+                    console.write(ch);
+                });
+    }
+
+    /**
+     * Write a formatted string to the kernel log.
+     *
+     * @param s Format string.
+     */
+    public static extern (C) void writef(string s, ...)
+    {
+        va_list args;
+        va_start(args, s);
+        writef(s, args);
+        va_end(args);
+    }
+
+    /**
+     * Write a formatted string and newline to the console.
+     *
+     * @param s Format string.
+     */
+    public static extern (C) void writefln(string s, ...)
+    {
+        va_list args;
+        va_start(args, s);
+        writef(s, args);
+        writef("\n", args);
+        va_end(args);
+    }
+}

src/hulk/linker_addresses.d

@@ -0,0 +1,139 @@
+/**
+ * This module provides access to linker-defined symbols.
+ */
+module hulk.linker_addresses;
+
+private extern extern(C) __gshared ubyte _hulk_header_start;
+private extern extern(C) __gshared ubyte _hulk_header_end;
+private extern extern(C) __gshared ubyte _hulk_header_size;
+
+private extern extern(C) __gshared ubyte _hulk_text_start;
+private extern extern(C) __gshared ubyte _hulk_text_end;
+private extern extern(C) __gshared ubyte _hulk_text_size;
+
+private extern extern(C) __gshared ubyte _hulk_rodata_start;
+private extern extern(C) __gshared ubyte _hulk_rodata_end;
+private extern extern(C) __gshared ubyte _hulk_rodata_size;
+
+private extern extern(C) __gshared ubyte _hulk_data_start;
+private extern extern(C) __gshared ubyte _hulk_data_end;
+private extern extern(C) __gshared ubyte _hulk_data_size;
+
+private extern extern(C) __gshared ubyte _hulk_bss_start;
+private extern extern(C) __gshared ubyte _hulk_bss_end;
+private extern extern(C) __gshared ubyte _hulk_bss_size;
+
+/* hulk_binary includes header, text, rodata, and data */
+private extern extern(C) __gshared ubyte _hulk_binary_size;
+
+/* hulk_mem includes header, text, rodata, data, and bss */
+private extern extern(C) __gshared ubyte _hulk_mem_start;
+private extern extern(C) __gshared ubyte _hulk_mem_end;
+private extern extern(C) __gshared ubyte _hulk_mem_size;
+
+/**
+ * This struct provides access to linker-defined symbols.
+ */
+public struct LinkerAddresses
+{
+    public static @property ulong hulk_header_start()
+    {
+        return cast(ulong)&_hulk_header_start;
+    }
+
+    public static @property ulong hulk_header_end()
+    {
+        return cast(ulong)&_hulk_header_end;
+    }
+
+    public static @property ulong hulk_header_size()
+    {
+        return cast(ulong)&_hulk_header_size;
+    }
+
+
+    public static @property ulong hulk_text_start()
+    {
+        return cast(ulong)&_hulk_text_start;
+    }
+
+    public static @property ulong hulk_text_end()
+    {
+        return cast(ulong)&_hulk_text_end;
+    }
+
+    public static @property ulong hulk_text_size()
+    {
+        return cast(ulong)&_hulk_text_size;
+    }
+
+
+    public static @property ulong hulk_rodata_start()
+    {
+        return cast(ulong)&_hulk_rodata_start;
+    }
+
+    public static @property ulong hulk_rodata_end()
+    {
+        return cast(ulong)&_hulk_rodata_end;
+    }
+
+    public static @property ulong hulk_rodata_size()
+    {
+        return cast(ulong)&_hulk_rodata_size;
+    }
+
+
+    public static @property ulong hulk_data_start()
+    {
+        return cast(ulong)&_hulk_data_start;
+    }
+
+    public static @property ulong hulk_data_end()
+    {
+        return cast(ulong)&_hulk_data_end;
+    }
+
+    public static @property ulong hulk_data_size()
+    {
+        return cast(ulong)&_hulk_data_size;
+    }
+
+
+    public static @property ulong hulk_bss_start()
+    {
+        return cast(ulong)&_hulk_bss_start;
+    }
+
+    public static @property ulong hulk_bss_end()
+    {
+        return cast(ulong)&_hulk_bss_end;
+    }
+
+    public static @property ulong hulk_bss_size()
+    {
+        return cast(ulong)&_hulk_bss_size;
+    }
+
+
+    public static @property ulong hulk_binary_size()
+    {
+        return cast(ulong)&_hulk_binary_size;
+    }
+
+
+    public static @property ulong hulk_mem_start()
+    {
+        return cast(ulong)&_hulk_mem_start;
+    }
+
+    public static @property ulong hulk_mem_end()
+    {
+        return cast(ulong)&_hulk_mem_end;
+    }
+
+    public static @property ulong hulk_mem_size()
+    {
+        return cast(ulong)&_hulk_mem_size;
+    }
+}

src/hulk/memory.d

@@ -0,0 +1,62 @@
+/**
+ * Memory-related functions.
+ */
+module hulk.memory;
+
+import ldc.llvmasm;
+
+void memset(void * dest, ubyte v, size_t n)
+{
+    __asm("rep stosb",
+          "{al},{rcx},{rdi},~{rcx},~{rdi},~{memory}",
+          v, n, dest);
+}
+
+void memset16(void * dest, ushort v, size_t n)
+{
+    __asm("rep stosw",
+          "{ax},{rcx},{rdi},~{rcx},~{rdi},~{memory}",
+          v, n, dest);
+}
+
+void memset32(void * dest, uint v, size_t n)
+{
+    __asm("rep stosl",
+          "{eax},{rcx},{rdi},~{rcx},~{rdi},~{memory}",
+          v, n, dest);
+}
+
+void memset64(void * dest, ulong v, size_t n)
+{
+    __asm("rep stosq",
+          "{rax},{rcx},{rdi},~{rcx},~{rdi},~{memory}",
+          v, n, dest);
+}
+
+void memcpy(void * dest, const(void) * src, size_t n)
+{
+    __asm("rep movsb",
+          "{rcx},{rsi},{rdi},~{rcx},~{rsi},~{rdi},~{memory}",
+          n, src, dest);
+}
+
+void memcpy16(void * dest, const(void) * src, size_t n)
+{
+    __asm("rep movsw",
+          "{rcx},{rsi},{rdi},~{rcx},~{rsi},~{rdi},~{memory}",
+          n, src, dest);
+}
+
+void memcpy32(void * dest, const(void) * src, size_t n)
+{
+    __asm("rep movsl",
+          "{rcx},{rsi},{rdi},~{rcx},~{rsi},~{rdi},~{memory}",
+          n, src, dest);
+}
+
+void memcpy64(void * dest, const(void) * src, size_t n)
+{
+    __asm("rep movsq",
+          "{rcx},{rsi},{rdi},~{rcx},~{rsi},~{rdi},~{memory}",
+          n, src, dest);
+}

src/hulk/mtrr.d

@@ -0,0 +1,70 @@
+/**
+ * MTRR (Memory Type Range Register) support for HULK.
+ */
+module hulk.mtrr;
+
+import hulk.cpu;
+import hulk.klog;
+
+enum ulong MTRR_TYPE_UC = 0u; /* Uncacheable */
+enum ulong MTRR_TYPE_WC = 1u; /* Write-Combining */
+enum ulong MTRR_TYPE_WT = 4u; /* Writethrough */
+enum ulong MTRR_TYPE_WP = 5u; /* Write-Protect */
+enum ulong MTRR_TYPE_WB = 6u; /* Writeback */
+
+enum uint MSR_MTRRCAP = 0xFEu;
+enum uint MSR_MTRRDEFTYPE = 0x2FFu;
+enum uint MSR_MTRRPHYSBASE0 = 0x200u;
+enum uint MSR_MTRRPHYSMASK0 = 0x201u;
+
+enum ulong MTRRCAP_WC = 0x400u;
+enum ulong MTRRCAP_FIX = 0x100u;
+enum ulong MTRRCAP_VCNT_MASK = 0xFFu;
+
+enum ulong MTRRDEFTYPE_E = 0x800u;
+enum ulong MTRRDEFTYPE_FE = 0x400u;
+enum ulong MTRRDEFTYPE_TYPE_MASK = 0xFFu;
+
+enum ulong MTRRPHYSBASE_PHYSBASE_MASK = 0x000F_FFFF_FFFF_F000u;
+enum ulong MTRRPHYSBASE_TYPE_MASK = 0xFFu;
+
+enum ulong MTRRPHYSMASK_PHYSMASK_MASK = 0x000F_FFFF_FFFF_F000u;
+enum ulong MTRRPHYSMASK_VALID = 0x800u;
+
+struct mtrr
+{
+    public static void initialize()
+    {
+        uint ebx;
+        uint ecx;
+        uint edx;
+        cpuid1(&ebx, &ecx, &edx);
+        if ((edx & CPUID_1_EDX_MTRR) == 0u)
+        {
+            klog.writefln("CPU does not support MTRR");
+            return;
+        }
+        const(ulong) mtrrcap = rdmsr(MSR_MTRRCAP);
+        const(ulong) mtrrdeftype = rdmsr(MSR_MTRRDEFTYPE);
+    }
+
+    private static ulong get_phys_base(uint n)
+    {
+        return rdmsr(MSR_MTRRPHYSBASE0 + 2u * n);
+    }
+
+    private static void set_phys_base(uint n, ulong physbase)
+    {
+        wrmsr(MSR_MTRRPHYSBASE0 + 2u * n, physbase);
+    }
+
+    private static ulong get_phys_mask(uint n)
+    {
+        return rdmsr(MSR_MTRRPHYSMASK0 + 2u * n);
+    }
+
+    private static void set_phys_mask(uint n, ulong physmask)
+    {
+        wrmsr(MSR_MTRRPHYSMASK0 + 2u * n, physmask);
+    }
+}

src/hulk/pagetable.d

@@ -0,0 +1,185 @@
+/**
+ * Page table structures.
+ */
+module hulk.pagetable;
+
+/** Page table entry attributes. @{ */
+enum ulong PT_PRESENT = 0x1u;
+enum ulong PT_WRITABLE = 0x2u;
+enum ulong PT_USER = 0x4u;
+enum ulong PT_WRITE_THROUGH = 0x8u;
+enum ulong PT_DISABLE_CACHE = 0x10u;
+enum ulong PT_ACCESSED = 0x20u;
+enum ulong PT_DIRTY = 0x40u;
+enum ulong PT_HUGE_PAGE = 0x80u;
+enum ulong PT_GLOBAL = 0x100u;
+enum ulong PT_NO_EXECUTE = 0x8000_0000_0000_0000u;
+/** @} */
+
+/** Page size in bytes. */
+enum ulong PAGE_SIZE = 4096u;
+
+/**
+ * Structure that represents a page table entry.
+ */
+struct PageTableEntry
+{
+    /** The raw page table entry is a 64-bit ulong. */
+    public ulong entry;
+    alias entry this;
+
+    /**
+     * Construct a page table entry.
+     *
+     * @param address
+     *   Address pointed to by the page table entry (ulong or pointer).
+     * @param flags
+     *   Page table flags (ORed set of PT_*).
+     */
+    this(T)(T address, ulong flags = 0u)
+    {
+        entry = cast(ulong)address | flags;
+    }
+
+    /**
+     * Return whether the page is present.
+     */
+    public @property bool present() const
+    {
+        return (entry & PT_PRESENT) != 0u;
+    }
+
+    /**
+     * Return whether the page is writable.
+     */
+    public @property bool writable() const
+    {
+        return (entry & PT_WRITABLE) != 0u;
+    }
+
+    /**
+     * Return whether the page is a user page.
+     */
+    public @property bool user() const
+    {
+        return (entry & PT_USER) != 0u;
+    }
+
+    /**
+     * Return whether the page is write-through.
+     */
+    public @property bool write_through() const
+    {
+        return (entry & PT_WRITE_THROUGH) != 0u;
+    }
+
+    /**
+     * Return whether the page has disable cache set.
+     */
+    public @property bool disable_cache() const
+    {
+        return (entry & PT_DISABLE_CACHE) != 0u;
+    }
+
+    /**
+     * Return whether the page is huge.
+     */
+    public @property bool huge() const
+    {
+        return (entry & PT_HUGE_PAGE) != 0u;
+    }
+
+    /**
+     * Return whether the page is global.
+     */
+    public @property bool global() const
+    {
+        return (entry & PT_GLOBAL) != 0u;
+    }
+
+    /**
+     * Return whether the page is no-execute.
+     */
+    public @property bool no_execute() const
+    {
+        return (entry & PT_NO_EXECUTE) != 0u;
+    }
+
+    /**
+     * Return whether the page is dirty.
+     */
+    public @property bool dirty() const
+    {
+        return (entry & PT_DIRTY) != 0u;
+    }
+
+    /**
+     * Return whether the page is accessed.
+     */
+    public @property bool accessed() const
+    {
+        return (entry & PT_ACCESSED) != 0u;
+    }
+
+    /**
+     * Follow the page table entry to the next page table it points to.
+     */
+    public PageTable * follow() const
+    {
+        return cast(PageTable *)(entry & 0x7FFF_FFFF_FFFF_F000u);
+    }
+}
+static assert(PageTableEntry.sizeof == 8u);
+
+/**
+ * Structure that represents a page table.
+ */
+struct PageTable
+{
+    /** Number of page table entries in a page table. */
+    enum size_t N_ENTRIES = 512u;
+
+    /** Page table entries. */
+    private PageTableEntry[N_ENTRIES] entries;
+
+    /**
+     * Access the PageTableEntry for the given address and page table level.
+     *
+     * @param address
+     *   Address to look up the page table entry (ulong or pointer).
+     * @param level
+     *   Page table level (0-4).
+     */
+    public PageTableEntry * entry(T)(T address, ulong level)
+    {
+        return &entries[index(cast(ulong)address, level)];
+    }
+
+    /**
+     * Determine the index into the page table for the given address and page
+     * table level.
+     *
+     * @param address
+     *   Address to look up the page table entry (ulong or pointer).
+     * @param level
+     *   Page table level (0-4).
+     */
+    public ulong index(T)(T address, ulong level)
+    {
+        return (cast(ulong)address >> (39u - (9u * level))) & 0x1FFu;
+    }
+
+    /**
+     * Access a page table entry by linear index.
+     *
+     * @param index
+     *   Page table index (0-511).
+     *
+     * @return PageTableEntry at the given index.
+     */
+    public PageTableEntry opIndex(size_t index)
+    {
+        return entries[index];
+    }
+}
+static assert(PageTable.sizeof == 4096u);

src/hulk/pci.d

@@ -0,0 +1,48 @@
+module hulk.pci;
+
+import hulk.cpu;
+import hulk.klog;
+
+struct pci
+{
+    /* IO address for PCI configuration address. */
+    enum IO_ADDR_CONFIG_ADDRESS = 0xCF8u;
+
+    /* IO address for PCI configuration data. */
+    enum IO_ADDR_CONFIG_DATA = 0xCFCu;
+
+    private static ulong read_config_register(ulong bus_id, ulong device_id, ulong register_id)
+    {
+        ulong addr = 0x8000_0000u | (bus_id << 16u) | (device_id << 11u) | (register_id << 2u);
+        out32(IO_ADDR_CONFIG_ADDRESS, addr);
+        return in32(IO_ADDR_CONFIG_DATA);
+    }
+
+    private static void scan(ulong bus_id, ulong device_id)
+    {
+        ulong reg0 = read_config_register(bus_id, device_id, 0u);
+        if (reg0 != 0xFFFFFFFFu)
+        {
+            ulong reg2 = read_config_register(bus_id, device_id, 2u);
+            klog.writefln("Found PCI device %04x:%04x (%02x:%02x:%02x) at %02u:%02u",
+                    (reg0 & 0xFFFFu), (reg0 >> 16u),
+                    (reg2 >> 24u) & 0xFFu,
+                    (reg2 >> 16u) & 0xFFu,
+                    (reg2 >> 8u) & 0xFFu,
+                    bus_id, device_id);
+        }
+    }
+
+    public static void initialize()
+    {
+        klog.writefln("Scanning PCI devices...");
+        for (ulong bus_id = 0u; bus_id < 256u; bus_id++)
+        {
+            for (ulong device_id = 0u; device_id < 32u; device_id++)
+            {
+                scan(bus_id, device_id);
+            }
+        }
+        klog.writefln("PCI scan complete.");
+    }
+}

src/hulk/pic.d

@@ -0,0 +1,16 @@
+/**
+ * PIC (Programmable Interrupt Controller) functionality.
+ */
+module hulk.pic;
+
+import hulk.cpu;
+
+struct pic
+{
+    public static void initialize()
+    {
+        /* Disable the PIC. */
+        out8(0xA1u, 0xFFu);
+        out8(0x21u, 0xFFu);
+    }
+}

src/hulk/pit.d

@@ -0,0 +1,42 @@
+/**
+ * PIT (Programmable Interval Timer) functionality.
+ */
+module hulk.pit;
+
+import hulk.cpu;
+import hulk.klog;
+
+struct pit
+{
+    /** PIT input frequency in 1/1000 Hz. */
+    private enum ulong PIT_FREQUENCY_1000HZ = 1_193_181_667u;
+    private enum ulong TARGET_INTERRUPT_HZ = 100u;
+    private enum ulong TARGET_INTERRUPT_1000HZ = TARGET_INTERRUPT_HZ * 1000u;
+    private enum ulong PIT_DIVIDER = (PIT_FREQUENCY_1000HZ + TARGET_INTERRUPT_1000HZ / 2u) / TARGET_INTERRUPT_1000HZ;
+
+    /** PIT channel 0 I/O port. */
+    private enum ubyte PORT_CH_0 = 0x40u;
+    /** PIT channel 1 I/O port. */
+    private enum ubyte PORT_CH_1 = 0x41u;
+    /** PIT channel 2 I/O port. */
+    private enum ubyte PORT_CH_2 = 0x42u;
+    /** PIT mode/command register I/O port. */
+    private enum ubyte PORT_MC = 0x43u;
+
+    private enum ubyte MC_CH_0 = 0x00u;
+    private enum ubyte MC_LO_HI = 0x30u;
+    private enum ubyte MC_RATE_GENERATOR = 0x04u;
+    private enum ubyte MC_BINARY = 0x00u;
+
+    public static void initialize()
+    {
+        out8(PORT_MC, MC_CH_0 | MC_LO_HI | MC_RATE_GENERATOR | MC_BINARY);
+        out8(PORT_CH_0, PIT_DIVIDER & 0xFFu);
+        out8(PORT_CH_0, PIT_DIVIDER >> 8u);
+    }
+
+    public static void isr()
+    {
+        klog.writefln("PIT ISR");
+    }
+}

src/hulk/rtc.d

@@ -0,0 +1,58 @@
+/**
+ * RTC (Real-Time Clock) functionality.
+ */
+module hulk.rtc;
+
+import hulk.cpu;
+import hulk.klog;
+import hulk.apic;
+
+struct rtc
+{
+    private enum ubyte PORT_SELECT = 0x70u;
+    private enum ubyte PORT_DATA = 0x71u;
+
+    private enum ubyte DISABLE_NMI = 0x80u;
+
+    private enum ubyte SR_A = 0xAu;
+    private enum ubyte SR_B = 0xBu;
+    private enum ubyte SR_C = 0xCu;
+
+    private enum ubyte SR_B_ENABLE_IRQ = 0x40u;
+
+    public static void initialize()
+    {
+        /* Enable IRQ 8 to receive RTC interrupts. */
+        out8(PORT_SELECT, DISABLE_NMI | SR_B);
+        ubyte sr_b = in8(PORT_DATA);
+        out8(PORT_SELECT, DISABLE_NMI | SR_B);
+        out8(PORT_DATA, sr_b | SR_B_ENABLE_IRQ);
+
+        out8(PORT_SELECT, DISABLE_NMI | SR_A);
+        klog.writefln("SR_A = 0x%x", in8(PORT_DATA));
+
+        /* Send EOI to enable more RTC interrupts and re-enable NMIs. */
+        eoi();
+    }
+
+    private static void eoi()
+    {
+        /* Read from status register C to clear the interrupt. */
+        out8(PORT_SELECT, SR_C);
+        in8(PORT_DATA);
+    }
+
+    public static void isr()
+    {
+        static __gshared ulong count;
+        static __gshared ulong seconds;
+        count++;
+        if ((count % 1024) == 0u)
+        {
+            seconds++;
+            klog.writefln("Seconds: %u", seconds);
+        }
+        eoi();
+        apic.eoi();
+    }
+}

src/hulk/writef.d

@@ -0,0 +1,151 @@
+/**
+ * HULK Formatted stream writing support.
+ */
+module hulk.writef;
+
+import core.stdc.stdarg;
+
+alias ch_out_fn = void function(ubyte);
+
+/**
+ * Format a string and write characters to the given output function.
+ *
+ * @param s Format string.
+ * @param args Variable arguments structure.
+ * @param ch_out Character output function.
+ *
+ * @return Number of characters written.
+ */
+size_t writef(string s, va_list args, ch_out_fn ch_out)
+{
+    size_t length_written;
+    bool escape = false;
+    char pad = ' ';
+    size_t width;
+    foreach (char c; s)
+    {
+        if (escape)
+        {
+            if (c == 'x')
+            {
+                ulong v;
+                va_arg(args, v);
+                length_written += write_hex(v, false, pad, width, ch_out);
+                escape = false;
+            }
+            else if (c == 'X')
+            {
+                ulong v;
+                va_arg(args, v);
+                length_written += write_hex(v, true, pad, width, ch_out);
+                escape = false;
+            }
+            else if (c == 'u')
+            {
+                ulong v;
+                va_arg(args, v);
+                length_written += write_udec(v, pad, width, ch_out);
+                escape = false;
+            }
+            else if ((c == '0') && (width == 0u))
+            {
+                pad = '0';
+            }
+            else if (('0' <= c) && (c <= '9'))
+            {
+                width = (width * 10u) + (c - '0');
+            }
+            else
+            {
+                ch_out(c);
+                escape = false;
+            }
+        }
+        else if (c == '%')
+        {
+            escape = true;
+            pad = ' ';
+            width = 0u;
+        }
+        else
+        {
+            ch_out(c);
+        }
+    }
+    return length_written;
+}
+
+/**
+ * Format a value in hexadecimal to the given output function.
+ *
+ * @param v Value to format.
+ * @param upper Whether to use uppercase letters.
+ * @param pad Pad character to use.
+ * @param width Field width.
+ * @param ch_out Character output function.
+ *
+ * @return Number of characters written.
+ */
+private size_t write_hex(ulong v, bool upper, char pad, size_t width, ch_out_fn ch_out)
+{
+    static __gshared const(char)[16] hex_chars_lower = "0123456789abcdef";
+    static __gshared const(char)[16] hex_chars_upper = "0123456789ABCDEF";
+    char[16] buf;
+    size_t i;
+    do
+    {
+        ulong n = v & 0xFu;
+        buf[i] = upper ? hex_chars_upper[n] : hex_chars_lower[n];
+        v >>= 4u;
+        i++;
+    } while (v != 0u);
+    size_t length_written = i;
+    while (width > i)
+    {
+        ch_out(pad);
+        width--;
+        length_written++;
+    }
+    do
+    {
+        i--;
+        ch_out(buf[i]);
+    } while (i != 0u);
+    return length_written;
+}
+
+/**
+ * Format a value in decimal to the given output function.
+ *
+ * @param v Value to format.
+ * @param pad Pad character to use.
+ * @param width Field width.
+ * @param ch_out Character output function.
+ *
+ * @return Number of characters written.
+ */
+private size_t write_udec(ulong v, char pad, size_t width, ch_out_fn ch_out)
+{
+    char[20] buf;
+    size_t i;
+    do
+    {
+        ulong d = v % 10u;
+        buf[i] = cast(char)(d + '0');
+        v /= 10u;
+        i++;
+    } while (v != 0u);
+    size_t length_written = i;
+    while (width > i)
+    {
+        ch_out(pad);
+        width--;
+        length_written++;
+    }
+    do
+    {
+        i--;
+        ch_out(buf[i]);
+    } while (i != 0u);
+    return length_written;
+}

x86_64-elf-gcc.rb

@@ -0,0 +1,76 @@
+project_name "x86_64-elf-gcc"
+binutils_version = "2.35"
+binutils_checksum = "1b11659fb49e20e18db460d44485f09442c8c56d5df165de9461eb09c8302f85"
+gcc_version = "10.2.0"
+gcc_checksum = "b8dd4368bb9c7f0b98188317ee0254dd8cc99d1e3a18d0ff146c855fe16c1d8c"
+install_path = File.expand_path("x86_64-elf-gcc")
+target = "x86_64-elf"
+path_prepend "#{install_path}/bin"
+
+configure do
+  check_c_compiler "gcc"
+  check_program "make"
+  check_program "bison"
+  check_program "flex"
+  check_program "texi2any", on_fail: "Install the texinfo package"
+  check_program "wget"
+  check_lib "gmp", on_fail: "Install the libgmp-dev package"
+  check_lib "mpc", on_fail: "Install the libmpc-dev package"
+  check_lib "mpfr", on_fail: "Install the libmpfr-dev package"
+end
+
+default do
+  unless Dir.exist?(install_path)
+    # Download archives.
+    download "https://ftp.gnu.org/gnu/binutils/binutils-#{binutils_version}.tar.xz",
+      "#{build_dir}/binutils-#{binutils_version}.tar.xz",
+      sha256sum: binutils_checksum
+
+    download "https://ftp.gnu.org/gnu/gcc/gcc-#{gcc_version}/gcc-#{gcc_version}.tar.xz",
+      "#{build_dir}/gcc-#{gcc_version}.tar.xz",
+      sha256sum: gcc_checksum
+
+    # Extract archives.
+    sh "tar", "xJf", "binutils-#{binutils_version}.tar.xz",
+      chdir: build_dir
+
+    sh "tar", "xJf", "gcc-#{gcc_version}.tar.xz",
+      chdir: build_dir
+
+    # Build binutils.
+    rm_rf "#{build_dir}/build-binutils"
+    mkdir_p "#{build_dir}/build-binutils"
+    cd "#{build_dir}/build-binutils" do
+      sh %W[../binutils-#{binutils_version}/configure
+        --target=#{target} --prefix=#{install_path} --with-sysroot --disable-nls
+        --disable-werror]
+      sh "make"
+      sh "make install"
+    end
+
+    # Build gcc.
+    rm_rf "#{build_dir}/build-gcc"
+    mkdir_p "#{build_dir}/build-gcc"
+    cd "#{build_dir}/build-gcc" do
+      sh %W[../gcc-#{gcc_version}/configure
+        --target=#{target} --prefix=#{install_path} --disable-nls
+        --enable-languages=c --without-headers]
+      sh "make all-gcc"
+      sh "make all-target-libgcc"
+      sh "make install-gcc"
+      sh "make install-target-libgcc"
+    end
+
+    # Remove archives and build directories if everything succeeded.
+    rm_f "#{build_dir}/binutils-#{binutils_version}.tar.xz"
+    rm_rf "#{build_dir}/binutils-#{binutils_version}"
+    rm_rf "#{build_dir}/build-binutils"
+    rm_f "#{build_dir}/gcc-#{gcc_version}.tar.xz"
+    rm_rf "#{build_dir}/gcc-#{gcc_version}"
+    rm_rf "#{build_dir}/build-gcc"
+  end
+end
+
+distclean do
+  rm_rf install_path
+end