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Diffstat (limited to 'boot/startup-x86_64.s')
| -rw-r--r-- | boot/startup-x86_64.s | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/boot/startup-x86_64.s b/boot/startup-x86_64.s index 448576a..6392d0f 100644 --- a/boot/startup-x86_64.s +++ b/boot/startup-x86_64.s @@ -11,7 +11,8 @@ MAX_MEM: equ 512 [GLOBAL startup] [GLOBAL pml4] [GLOBAL pdp] - +[GLOBAL mb_magic] +[GLOBAL mb_info_addr] ; functions from other parts of rustubs [EXTERN vectors_start] [EXTERN idt] @@ -28,6 +29,12 @@ MAX_MEM: equ 512 startup: cld cli + ; with multiboot specs, grub initialzes the registers: + ; EAX: magic value 0x2BADB002 + ; EBX: 32-bit physical address of the multiboot information struct + ; we store them in global variables for future uses in rust code. + mov dword [mb_magic], eax + mov dword [mb_info_addr], ebx ; setup GDT by loading GDT descriptor ; see docs/x86_gdt.txt lgdt [gdt_80] @@ -156,6 +163,11 @@ gdt_80: dw 4*8 - 1 ; GDT limit=24, 4 GDT entries - 1 dq gdt ; GDT address +; multiboot info +mb_magic: + dd 0x00000000 +mb_info_addr: + dd 0x00000000 [SECTION .bss] |