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| author | Kartik K. Agaram <vc@akkartik.com> | 2021-03-14 22:46:03 -0700 |
|---|---|---|
| committer | Kartik K. Agaram <vc@akkartik.com> | 2021-03-14 22:46:03 -0700 |
| commit | dda5fd08d8920b247b1880ff7d28dc7f4db60617 (patch) | |
| tree | 0f2f2c845b112b4fefffe9415b0ce713ed30e27d | |
| parent | 0e5d7e06248c22f663ce6d65e88676dba12f5a48 (diff) | |
| download | mu-dda5fd08d8920b247b1880ff7d28dc7f4db60617.tar.gz | |
.
| -rw-r--r-- | boot.subx | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/boot.subx b/boot.subx index f43bac65..b8b34c4a 100644 --- a/boot.subx +++ b/boot.subx @@ -156,15 +156,26 @@ == code cd/syscall 0x10/imm8/bios-video-services -== data - # switch to 32-bit mode - 0f 01 16 # lgdt 00/mod/indirect 010/subop 110/rm/use-disp16 + # . load global descriptor table + 0f 01/lgdt 0/mod/indirect 2/subop/lgdt 6/rm32/use-disp16 +== data f8 7c # *gdt_descriptor [label] - 0f 20 c0 # eax <- cr0 +== code + # . enable paging + 0f 20/cr-> 3/mod/direct 0/rm32/cr0 0/r32/eax +== data + # TODO: SubX doesn't understand 66 prefix +#? 66 83/or 3/mod/direct 0/rm32/eax 1/r32/?? 1/imm8 # eax <- or 0x1 66 83 c8 01 # eax <- or 0x1 - 0f 22 c0 # cr0 <- eax +== 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 + +== data # padding # 8e: |