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Merge pull request #7 from phil-opp/fix_long_mode_test

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Fix long mode test
This commit is contained in:
Philipp Oppermann
2015-10-25 01:51:43 +02:00
parent 9cd9ec25db f670e330f5
commit 68c0ab0d59
1 changed files with 9 additions and 9 deletions
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18
src/arch/x86_64/boot.asm
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@@ -20,9 +20,9 @@ bits 32
start:
mov esp, stack_top
call check_multiboot
call check_cpuid
call check_long_mode
call test_multiboot
call test_cpuid
call test_long_mode
call setup_page_tables
call enable_paging
@@ -83,7 +83,7 @@ error:
hlt
; Throw error 0 if eax doesn't contain the Multiboot 2 magic value (0x36d76289).
check_multiboot:
test_multiboot:
cmp eax, 0x36d76289
jne .no_multiboot
ret
@@ -92,7 +92,7 @@ check_multiboot:
jmp error
; Throw error 1 if the CPU doesn't support the CPUID command.
check_cpuid:
test_cpuid:
pushfd ; Store the FLAGS-register.
pop eax ; Restore the A-register.
mov ecx, eax ; Set the C-register to the A-register.
@@ -111,15 +111,15 @@ check_cpuid:
jmp error
; Throw error 2 if the CPU doesn't support Long Mode.
check_long_mode:
test_long_mode:
mov eax, 0x80000000 ; Set the A-register to 0x80000000.
cpuid ; CPU identification.
cmp eax, 0x80000001 ; Compare the A-register with 0x80000001.
jb .no_long_mode ; It is less, there is no long mode.
mov eax, 0x80000000 ; Set the A-register to 0x80000000.
mov eax, 0x80000001 ; Set the A-register to 0x80000001.
cpuid ; CPU identification.
cmp eax, 0x80000001 ; Compare the A-register with 0x80000001.
jb .no_long_mode ; It is less, there is no long mode.
test edx, 1 << 29 ; Test if the LM-bit, which is bit 29, is set in the D-register.
jz .no_long_mode ; They aren't, there is no long mode.
ret
.no_long_mode:
mov al, "2"