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| author | Kartik Agaram <vc@akkartik.com> | 2020-12-20 20:03:02 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2020-12-20 20:03:02 -0800 |
| commit | 72e34ecb63d0d26ed0568702344e44b6034227bd (patch) | |
| tree | ac5473dfa8dae0f8daa130a94c3c9f2b8703b1ca | |
| parent | 02135b7ae8ca3e4515ae3b9ee0940ba212e11676 (diff) | |
| download | mu-72e34ecb63d0d26ed0568702344e44b6034227bd.tar.gz | |
7360
Insert padding in a few places so we don't have to recalculate addresses quite so much.
| -rw-r--r-- | apps/bos/32bit.hex | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/apps/bos/32bit.hex b/apps/bos/32bit.hex index 80852c4c..8b396fcd 100644 --- a/apps/bos/32bit.hex +++ b/apps/bos/32bit.hex @@ -20,15 +20,19 @@ # 00: fa 0f 01 16 # lgdt 00/mod/indirect 010/subop 110/rm32/TODO - 2d 7c # *gdt_descriptor + 38 7c # *gdt_descriptor 0f 20 c0 # eax <- cr0 66 83 c8 01 # eax <- or 0x1 0f 22 c0 # cr0 <- eax - ea 33 7c 08 00 # far jump to initialize_32bit_mode after setting cs to the record at offset 8 in the gdt (gdt_code) + ea 50 7c 08 00 # far jump to initialize_32bit_mode after setting cs to the record at offset 8 in the gdt (gdt_code) + +# padding +# 15: + 00 00 00 00 00 00 00 00 00 00 00 ## GDT: 3 records of 8 bytes each -# 15: +# 20: # gdt_start: # gdt_null: mandatory null descriptor 00 00 00 00 00 00 00 00 @@ -49,14 +53,20 @@ 00 # base[24:32] # gdt_end: -# 2d: +# 38: # gdt_descriptor: 17 00 # final index of gdt = gdt_end - gdt_start - 1 - 15 7c 00 00 # start = gdt_start + 20 7c 00 00 # start = gdt_start + +# padding +# 3e: + 00 00 +# 40: + 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ## 32-bit code from this point (still some instructions not in SubX) -# 33: +# 50: # initialize_32bit_mode: 66 b8 10 00 # ax <- offset 16 from gdt_start 8e d8 # ds <- ax @@ -64,16 +74,15 @@ 8e c0 # es <- ax 8e e0 # fs <- ax 8e e8 # gs <- ax -# 40: - e9 0a 00 00 00 # jump to 0x7c50, leaving some extra padding + e9 0d 00 00 00 # jump to 0x7c70, leaving some extra padding # padding -# 45: - 00 00 00 00 00 00 00 00 00 00 +# 63: + 00 00 00 00 00 00 00 00 00 00 00 00 00 ## 'application' SubX code: print one character to top-left of screen -# 50: +# 70: # *0xb8000 <- 0x0f48 c7 # opcode # modrm @@ -89,8 +98,7 @@ e9 fd ff # loop forever # more padding to 512 bytes 00 00 00 -00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 -00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 +# 80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |