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unreal gdt tweaks & fixes

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This commit is contained in:
Elaina Claus
2024-10-13 13:22:01 -04:00
parent 3d1877d7fe
commit 963dec5281
1 changed files with 9 additions and 13 deletions
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22
src/stage2/stage2.nasm
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@@ -396,27 +396,23 @@ ALIGN 16, db 0
unreal_gdt_info:
unreal_gdt_size: dw (unreal_gdt_end - unreal_gdt_start) - 1
unreal_gdt_ptr: dd ((__STAGE2_SEGMENT << 4) + unreal_gdt_start)
unreal_gdt_start:
; entry 0 (null descriptor)
dq 0 ; first entry is null
; entry 1 (16-bit code segment with 4 GiB flat mapping)
dw 0xFFFF ; Segment Limit 15:0
dw 0x0000 ; Base Address 15:0
db 0000_0000b ; Base Address 23:16
db 1001_1010b ; Access Byte: executable, readable, present
db 1000_1111b ; 24:20 G/DB/L/AVL & SegLimit 19:16
dq 0x0000FFFF ; Base Address(15:0) 31:16, Segment Limit(15:0) 15:0
db 0x00 ; Base Address 23:16
db 1001_1010b ; Access Byte: Present, ring0, S = 1, executable (1), non-conforming, readable, Accessed
db 1000_1111b ; Flags: GR = 4KiB, attr = <DB/L/Avl>, Granularity = 4KiB & 16:19 of limit
db 0000_0000b ; Base Address 31:24
; entry 2 (16-bit data segment with 4 GiB flat mapping)
dw 0xFFFF ; Segment Limit 15:0
dw 0x0000 ; Base Address 15:0
db 0000_0000b ; Base Address 23:16
db 1001_0010b ; Access Byte: readable, writable, present
db 1000_1111b ; Flags: 16-bit, Granularity = 4KiB
db 0000_0000b ; Base Address 31:24
dq 0x0000FFFF ; Base Address(15:0) 31:16, Segment Limit(15:0) 15:0
db 0x00 ; Base Address(23:16)
db 1001_0010b ; Access Byte: Present, ring0, S = 1, data (0), non-confirming, writable, present
db 1000_1111b ; Flags: GR = 4KiB, attr = <16-bit/?/?>, Granularity = 4KiB & 16:19 of limit
db 0000_0000b ; Base Address(31:24)
unreal_gdt_end:
ALIGN 16, db 0