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realigned assembly a bit

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git-svn-id: svn://anubis/hos/trunk@18 5b3e749e-e535-0410-8002-a9bb6afbdfca
This commit is contained in:
josh 2009-06-25 19:12:25 +00:00
parent 1b0da72e5a
commit 8fe8d78051
1 changed files with 56 additions and 45 deletions
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101
kernel/boot.asm
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@ -14,9 +14,11 @@
%define PAGE_SIZE 0x1000 ; 4KB pages
; Get these symbols from the linker
; Symbols from the linker
extern _end, _bss
; Symbols from C
extern k_mbsave
;-------------------------------------------------------
[section .text]
@ -30,80 +32,89 @@ start:
;**************************************************************************
;* Multiboot header data block *
;**************************************************************************
align 4
align 4
multiboot_header:
dd MULTIBOOT_HEADER_MAGIC ; magic
dd MULTIBOOT_HEADER_FLAGS ; flags
dd -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS) ; checksum
dd MULTIBOOT_HEADER_MAGIC ; magic
dd MULTIBOOT_HEADER_FLAGS ; flags
dd -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS) ; checksum
dd multiboot_header - VIRTUAL_OFFSET ; header_addr
dd start - VIRTUAL_OFFSET ; load_addr
dd _bss - VIRTUAL_OFFSET ; load_end_addr
dd _end - VIRTUAL_OFFSET ; bss_end_addr
dd multiboot_entry - VIRTUAL_OFFSET ; entry_addr
dd multiboot_header - VIRTUAL_OFFSET ; header_addr
dd start - VIRTUAL_OFFSET ; load_addr
dd _bss - VIRTUAL_OFFSET ; load_end_addr
dd _end - VIRTUAL_OFFSET ; bss_end_addr
dd multiboot_entry - VIRTUAL_OFFSET ; entry_addr
;**************************************************************************
;* Resume execution *
;**************************************************************************
multiboot_entry:
mov ax, 0x0700 + 'a'
mov [0xB8000+160*8+0*2], ax
mov ax, 0x0700 + 'a'
mov [0xB8000+160*8+0*2], ax
lgdt [gdtr_tmp32-VIRTUAL_OFFSET] ; load temporary GDTR
jmp KERNEL_CODE_32_TMP_SEG:segmented_start
lgdt [gdtr_tmp32-VIRTUAL_OFFSET] ; load temporary GDTR
jmp KERNEL_CODE_32_TMP_SEG:segmented_start
;**************************************************************************
;* At this point address 0xE000_0000 is mapped to physical address 0x0 *
;**************************************************************************
segmented_start:
mov cx, KERNEL_DATA_32_TMP_SEG
mov ss, cx
mov ds, cx
mov es, cx
mov gs, cx
mov fs, cx
mov esp, TEMPORARY_STACK_VIRTUAL-4 ; set up temporary stack space
mov cx, KERNEL_DATA_32_TMP_SEG
mov ss, cx
mov ds, cx
mov es, cx
mov gs, cx
mov fs, cx
mov esp, TEMPORARY_STACK_VIRTUAL-4 ; set up temporary stack space
mov ax, 0x0700 + 'b'
mov [VIRTUAL_OFFSET+0xB8000+160*8+1*2], ax
mov ax, 0x0700 + 'b'
mov [VIRTUAL_OFFSET+0xB8000+160*8+1*2], ax
; add ebx, VIRTUAL_OFFSET
; push eax
; push ebx ; pointer to multiboot info struct
; call k_mbsave
; add esp, 8
; mov ax, 0x0700 + 'c'
; mov [VIRTUAL_OFFSET+0xB8000+160*8+2*2], ax
idle_loop:
hlt
jmp idle_loop
jmp idle_loop
;-------------------------------------------------------
[section .rodata]
gdtr_tmp32:
dw gdt_end_tmp32-gdt_tmp32-1
dd gdt_tmp32-VIRTUAL_OFFSET
dw gdt_end_tmp32-gdt_tmp32-1
dd gdt_tmp32-VIRTUAL_OFFSET
gdt_tmp32: ; 0 = null descriptor
dd 0
dd 0
gdt_tmp32: ; 0 = null descriptor
dd 0
dd 0
; a base of 0x2000_0000, when added to 0xE000_0000 will produce
; 0x0000_0000 physical before paging in effect
KERNEL_CODE_32_TMP_SEG equ $-gdt_tmp32 ; 8
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 0x20 ;base 31:24
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 0x20 ; base 31:24
KERNEL_DATA_32_TMP_SEG equ $-gdt_tmp32 ; 16
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 0x20 ;base 31:24
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 0x20 ; base 31:24
gdt_end_tmp32: