m1x/x86_64: Add GDT groundwork

Signed-off-by: Ian Moffett <ian@mirocom.org>
2026-03-25 04:56:26 -04:00
parent 4d3ef344f8
commit c6b00af6c7
1 changed files with 75 additions and 0 deletions
--- a/src/m1x/arch/x86_64/cpu/locore.S
+++ b/src/m1x/arch/x86_64/cpu/locore.S
@@ -15,3 +15,78 @@ _start:

 1:  hlt
    jmp 1b
+
+md_cpu_lgdt:
+    push %r12
+    push %r13
+    push %r14
+    push %r15
+    push %rbx
+
+    lgdt (%rdi)
+    push $0x08
+    lea 1f(%rip), %rbx
+    push %rbx
+    lretq
+
+1:  mov $0x10, %ax
+    mov %ax, %ds
+    mov %ax, %es
+    mov %ax, %ss
+    xor %ax, %ax
+    mov %ax, %fs
+    mov %ax, %gs
+
+    pop %rbx
+    pop %r15
+    pop %r14
+    pop %r13
+    pop %r12
+    retq
+
+     .section .data
+    .globl g_GDT
+g_GDT:
+.NULL:
+    .word 0x0000
+    .word 0x0000
+    .byte 0x00
+    .byte 0b00000000
+    .byte 0b00000000
+    .byte 0x00
+.CODE:
+    .word 0x0000
+    .word 0x0000
+    .byte 0x00
+    .byte 0b10011010
+    .byte 0b00100000
+    .byte 0x00
+.DATA:
+    .word 0x0000
+    .word 0x0000
+    .byte 0x00
+    .byte 0b10010010
+    .byte 0b00000000
+    .byte 0x00
+.UCODE:
+    .word 0x0000
+    .word 0x0000
+    .byte 0x00
+    .byte 0b11111010
+    .byte 0b10101111
+    .byte 0x00
+.UDATA:
+    .word 0x0000
+    .word 0x0000
+    .byte 0x00
+    .byte 0b11110010
+    .byte 0b00000000
+    .byte 0x00
+.TSS:
+    .quad 0x00
+    .quad 0x00
+
+    .globl g_GDTR
+g_GDTR:
+    .word g_GDTR - g_GDT
+    .quad g_GDT