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Some simplification and commenting

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This commit is contained in:
Thomas Lovén 2017-11-15 20:37:22 +01:00
parent 93d60294ba
commit 4f9a4292e5
2 changed files with 45 additions and 40 deletions
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21
src/kernel/boot/boot.S
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@ -12,19 +12,32 @@ BootStack:
.code32
error:
// Print "ERR!" in upper left corner
mov [0xb8000], dword ptr 0x4f524f45
mov [0xb8004], dword ptr 0x4f214f52
mov [0xb8000], dword ptr 0x4f004f00
mov [0xb8004], dword ptr 0x4f004f00
mov [0xb8000], byte ptr 'E'
mov [0xb8002], byte ptr 'R'
mov [0xb8004], byte ptr 'R'
mov [0xb8006], byte ptr '!'
jmp $
check_cpuid:
// Save EFLAGS
pushfd
// Try to modify EFLAGS.ID
pushfd
xor dword ptr [esp], 1<<21
popfd
//Read EFLAGS into eax
pushfd
pop eax
xor eax, [esp]
// Restore original EFLAGS
popfd
// Check if EFLAGS.ID was modified
xor eax, [esp+4]
and eax, 1<<21
jz error
ret
@ -72,8 +85,6 @@ mov cr0, eax
lgdt [BootGDTp]
.extern long_mode_start
jmp 0x8:long_mode_start
.code64

12
src/kernel/boot/boot_PT.S
View File

@ -7,16 +7,10 @@
BootP4:
.quad offset BootP3 + (PAGE_PRESENT | PAGE_WRITE)
.rept ENTRIES_PER_PT - 1
.quad 0x0
.quad 0
.endr
BootP3:
.quad offset BootP2 + (PAGE_PRESENT | PAGE_WRITE)
.quad 0 + (PAGE_PRESENT | PAGE_WRITE | PAGE_HUGE)
.rept ENTRIES_PER_PT - 1
.quad 0x0
.endr
BootP2:
.set i, 0
.rept ENTRIES_PER_PT
.quad (i << 21 ) + (PAGE_PRESENT | PAGE_WRITE | PAGE_HUGE)
.set i, (i+1)
.quad 0
.endr