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| author | Kartik Agaram <vc@akkartik.com> | 2020-12-23 09:57:40 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2020-12-23 10:04:01 -0800 |
| commit | d70711e1b0cce6e9b6c4bd7a4775f218e220e3b2 (patch) | |
| tree | 3fd3475e2c33afc8aa773185b106057ab009f3c9 /apps | |
| parent | f29b6c6b1abf167ccb3527635edd69834ea83e80 (diff) | |
| download | mu-d70711e1b0cce6e9b6c4bd7a4775f218e220e3b2.tar.gz | |
7384
Currently at commit 7378 (reset the A20 address line) except without 7376 (enabling interrupts).
Diffstat (limited to 'apps')
| -rw-r--r-- | apps/boot.hex | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/apps/boot.hex b/apps/boot.hex index ffb4b277..d09287a8 100644 --- a/apps/boot.hex +++ b/apps/boot.hex @@ -62,19 +62,38 @@ 0f 82 76 00 # jump-if-carry disk-error # 26: + # undo the A20 hack: https://en.wikipedia.org/wiki/A20_line + # this is from https://github.com/mit-pdos/xv6-public/blob/master/bootasm.S + # seta20.1: + e4 64 # al <- port 0x64 + a8 02 # set zf if bit 1 (second-least) is not set + 75 fa # if zf not set, goto seta20.1 (-6) + + b0 d1 # al <- 0xd1 + e6 64 # port 0x64 <- al + +# 30: + # seta20.2: + e4 64 # al <- port 0x64 + a8 02 # set zf if bit 1 (second-least) is not set + 75 fa # if zf not set, goto seta20.2 (-6) + + b0 df # al <- 0xdf + e6 64 # port 0x64 <- al + +# 3a: # switch to 32-bit mode 0f 01 16 # lgdt 00/mod/indirect 010/subop 110/rm32/TODO 80 7c # *gdt_descriptor -# 2b: +# 3f: 0f 20 c0 # eax <- cr0 66 83 c8 01 # eax <- or 0x1 0f 22 c0 # cr0 <- eax ea c0 7c 08 00 # far jump to initialize_32bit_mode after setting cs to the record at offset 8 in the gdt (gdt_code) # padding -# 3a: - 00 00 00 00 00 00 -00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 +# 4e: + 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ## GDT: 3 records of 8 bytes each |