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| author | Kartik K. Agaram <vc@akkartik.com> | 2021-03-14 23:24:02 -0700 |
|---|---|---|
| committer | Kartik K. Agaram <vc@akkartik.com> | 2021-03-14 23:24:02 -0700 |
| commit | ee81002eb06285e3b13754e95d513f1ac79f4827 (patch) | |
| tree | 8a453efe34b62864ca93a49e6298035bb66e341e /boot.subx | |
| parent | 5c1186a77b917625171aebf8abf2bc9e6a911114 (diff) | |
| download | mu-ee81002eb06285e3b13754e95d513f1ac79f4827.tar.gz | |
.
Diffstat (limited to 'boot.subx')
| -rw-r--r-- | boot.subx | 20 |
1 files changed, 8 insertions, 12 deletions
diff --git a/boot.subx b/boot.subx index 0db21e32..dd01f409 100644 --- a/boot.subx +++ b/boot.subx @@ -164,10 +164,8 @@ 66 83 c8 01 # eax <- or 0x1 == code 0f 22/cr<- 3/mod/direct 0/rm32/cr0 0/r32/eax -== data # . far jump that sets cs to offset 8 in the gdt in the process - ea 00 7d 08 00 # far jump to initialize_32bit_mode after setting cs to the record at offset 8 in the gdt (gdt_code) [label] -== code + ea/jump-far-absolute 0x00087d00/disp32 # address 0x7d00 in offset 8 of the gdt == data @@ -197,11 +195,10 @@ disk_error: ## GDT: 3 records of 8 bytes each == data -# e0: -# gdt_start: -# gdt_null: mandatory null descriptor +gdt_start: +# offset 0: gdt_null: mandatory null descriptor 00 00 00 00 00 00 00 00 -# gdt_code: (offset 8 from gdt_start) +# offset 8: gdt_code ff ff # limit[0:16] 00 00 00 # base[0:24] 9a # 1/present 00/privilege 1/descriptor type = 1001b @@ -209,7 +206,7 @@ disk_error: cf # 1/granularity 1/32-bit 0/64-bit-segment 0/AVL = 1100b # limit[16:20] = 1111b 00 # base[24:32] -# gdt_data: (offset 16 from gdt_start) +# offset 16: gdt_data ff ff # limit[0:16] 00 00 00 # base[0:24] 92 # 1/present 00/privilege 1/descriptor type = 1001b @@ -218,10 +215,9 @@ disk_error: 00 # base[24:32] # gdt_end: -# f8: -# gdt_descriptor: - 17 00 # final index of gdt = gdt_end - gdt_start - 1 - e0 7c 00 00 # start = gdt_start [label] +gdt_descriptor: + 0x17/imm16 # final index of gdt = size of gdt - 1 + gdt_start/imm32/start # padding # fe: |