Rework scanning MADT table entries

Get I/O APIC address from MADT entry.
Add DEBUG flag for APIC.
Show number of CPUs found.

Rsconscript

@@ -199,6 +199,7 @@ task "run", desc: "Run HOS in QEMU" do
     qemu-system-x86_64
     -machine q35
     -cpu max
+    -smp cpus=4
     -serial file:qemu/serial.out
     -bios #{ovmf}
     -drive file=qemu/HOS.img,format=raw

src/hulk/apic.d

@@ -13,6 +13,8 @@ import hulk.memory;
 
 struct Apic
 {
+    private enum DEBUG = false;
+    private enum DEFAULT_IO_APIC_ADDRESS = 0xFEC0_0000u;
     private enum uint PERIODIC_MODE = 0x2_0000u;
 
     private enum ulong IRQ_PIT = 2u;
@@ -28,16 +30,112 @@ struct Apic
          */
         static struct Entry
         {
+            enum PROCESSOR_LOCAL_APIC = 0;
+            enum IO_APIC = 1;
+            enum IO_APIC_INTERRUPT_SOURCE_OVERRIDE = 2;
+            enum IO_APIC_NMI_SOURCE = 3;
+            enum LOCAL_APIC_NMI = 4;
             enum LOCAL_APIC_ADDRESS_OVERRIDE = 5;
+            enum PROCESSOR_LOCAL_X2APIC = 9;
 
             ubyte type;
             ubyte length;
         }
 
+        /**
+         * Processor Local APIC.
+         */
+        static struct Entry0
+        {
+            Entry header;
+            ubyte acpi_processor_id;
+            ubyte apic_id;
+            uint flags;
+        }
+        static assert(Entry0.sizeof == 8);
+
+        /**
+         * I/O APIC.
+         */
+        static struct Entry1
+        {
+            Entry header;
+            ubyte io_apic_id;
+            ubyte _reserved;
+            uint io_apic_address;
+            uint global_system_interrupt_base;
+        }
+        static assert(Entry1.sizeof == 12);
+
+        /**
+         * IO/APIC Interrupt Source Override.
+         */
+        static struct Entry2
+        {
+            Entry header;
+            ubyte bus_source;
+            ubyte irq_source;
+            uint global_system_interrupt;
+            ushort flags;
+            ushort _reserved;
+        }
+        static assert(Entry2.sizeof == 12);
+
+        /**
+         * IO/APIC Non-maskable interrupt source.
+         */
+        static struct Entry3
+        {
+            Entry header;
+            ubyte nmi_source;
+            ubyte _reserved;
+            ushort flags;
+            ubyte[4] global_system_interrupt;
+        }
+        static assert(Entry3.sizeof == 10);
+
+        /**
+         * Local APIC Non-maskable interrupts.
+         */
+        static struct Entry4
+        {
+            Entry header;
+            ubyte acpi_processor_id;
+            ubyte[2] flags;
+            ubyte lint_nr;
+        }
+        static assert(Entry4.sizeof == 6);
+
+        /**
+         * Local APIC Address Override.
+         */
+        static struct Entry5
+        {
+            Entry header;
+            ushort _reserved;
+            ubyte[8] local_apic_address;
+        }
+        static assert(Entry5.sizeof == 12);
+
+        /**
+         * Processor Local x2APIC.
+         */
+        static struct Entry9
+        {
+            Entry header;
+            ushort _reserved;
+            uint local_x2apic_id;
+            uint flags;
+            uint acpi_id;
+        }
+        static assert(Entry9.sizeof == 16);
+
         Acpi.Header header;
         uint local_apic_address;
         uint flags;
 
+        static assert(MADT.sizeof == 0x2C);
+
         /**
          * Scan the MADT table.
          */
@@ -46,14 +144,99 @@ struct Apic
             apic_registers = cast(ApicRegisters *)local_apic_address;
             const(void) * end = cast(const(void) *)(&this) + header.length;
             const(Entry) * entry = cast(const(Entry) *)(cast(ulong)&this + MADT.sizeof);
+            bool first_io_apic = true;
+            size_t n_cpus = 0u;
             while (entry < end)
             {
-                entry = cast(const(Entry) *)(cast(size_t)entry + entry.length);
-                if (entry.type == Entry.LOCAL_APIC_ADDRESS_OVERRIDE)
+                if (DEBUG)
                 {
-                    /* Found a 64-bit Local APIC Address Override entry. */
-                    memcpy(cast(void *)&apic_registers, cast(const(void) *)entry + 4u, apic_registers.sizeof);
+                    Klog.writefln("MADT entry type %u, length %u", entry.type, entry.length);
                 }
+                switch (entry.type)
+                {
+                case Entry.PROCESSOR_LOCAL_APIC:
+                    Entry0 * e = cast(Entry0 *)entry;
+                    n_cpus++;
+                    if (DEBUG)
+                    {
+                        Klog.writefln("  ACPI processor ID: %u, APIC ID: %u, Flags: 0x%x",
+                                e.acpi_processor_id, e.apic_id, e.flags);
+                    }
+                    break;
+
+                case Entry.IO_APIC:
+                    Entry1 * e = cast(Entry1 *)entry;
+                    if (first_io_apic)
+                    {
+                        io_apic_registers = cast(IoApicRegisters *)e.io_apic_address;
+                        first_io_apic = false;
+                    }
+                    if (DEBUG)
+                    {
+                        Klog.writefln("  I/O APIC ID: %u, I/O APIC Address: 0x%x, GSIB: %u",
+                                e.io_apic_id, e.io_apic_address, e.global_system_interrupt_base);
+                    }
+                    break;
+
+                case Entry.IO_APIC_INTERRUPT_SOURCE_OVERRIDE:
+                    Entry2 * e = cast(Entry2 *)entry;
+                    if (DEBUG)
+                    {
+                        Klog.writefln("  Bus %u IRQ %u GSI %u Flags: 0x%x",
+                                e.bus_source, e.irq_source, e.global_system_interrupt, e.flags);
+                    }
+                    break;
+
+                case Entry.IO_APIC_NMI_SOURCE:
+                    Entry3 * e = cast(Entry3 *)entry;
+                    if (DEBUG)
+                    {
+                        uint global_system_interrupt;
+                        memcpy(&global_system_interrupt, &e.global_system_interrupt, 4u);
+                        Klog.writefln("  NMI Source: %u, Flags: 0x%x, GSI: %u",
+                                e.nmi_source, e.flags, global_system_interrupt);
+                    }
+                    break;
+
+                case Entry.LOCAL_APIC_NMI:
+                    Entry4 * e = cast(Entry4 *)entry;
+                    if (DEBUG)
+                    {
+                        ushort flags;
+                        memcpy(&flags, &e.flags, 2u);
+                        Klog.writefln("  ACPI Processor ID: %u, Flags: 0x%x, LINT#: %u",
+                                e.acpi_processor_id, flags, e.lint_nr);
+                    }
+                    break;
+
+                case Entry.LOCAL_APIC_ADDRESS_OVERRIDE:
+                    Entry5 * e = cast(Entry5 *)entry;
+                    if (DEBUG)
+                    {
+                        memcpy(&apic_registers, &e.local_apic_address, 8u);
+                        Klog.writefln("  Local APIC Address: 0x%x", apic_registers);
+                    }
+                    break;
+
+                case Entry.PROCESSOR_LOCAL_X2APIC:
+                    Entry9 * e = cast(Entry9 *)entry;
+                    if (DEBUG)
+                    {
+                        Klog.writefln("  x2APIC ID: %u, Flags: 0x%x, ACPI ID: %u",
+                                e.local_x2apic_id, e.flags, e.acpi_id);
+                    }
+                    break;
+
+                default:
+                    break;
+                }
+
+                /* Move to next entry. */
+                entry = cast(const(Entry) *)(cast(size_t)entry + entry.length);
+            }
+            if (n_cpus > 0u)
+            {
+                Klog.writefln("%u CPU(s) found", n_cpus);
             }
         }
     }
@@ -122,7 +305,7 @@ struct Apic
     public static void initialize()
     {
         Klog.writefln("\a3Initializing APIC");
-        io_apic_registers = cast(IoApicRegisters *)0xFEC0_0000u;
+        io_apic_registers = cast(IoApicRegisters *)DEFAULT_IO_APIC_ADDRESS;
         MADT * madt = cast(MADT *)Acpi.get_table("APIC");
         madt.scan();
         Klog.writefln("APIC found at %p", apic_registers);