> Date: Wed, 5 Sep 2012 04:01:56 +0400 > From: Alexander Polakov <p...@sdf.org> > > * Alexander Polakov <p...@sdf.org> [120903 21:41]: > > Now back to "underlying issues": x86emu executes some code which causes > > parity check NMI (bit 7 set in port 0x61) to be generated, which causes > > drop to the debugger (I mistook it for a panic). > > Nobody asked me which code exactly. But I'll tell you anyway. > > 000C1867 56 push si > 000C1868 BE 38 02 mov si, 0x0238 > 000C186B 8B 34 mov si, [si] > 000C186D 8B 74 10 mov si, [si+0x10] > 000C1870 83 C6 04 add si, 0x04 > 000C1873 FC cld > 000C1874 B9 07 00 mov cx, 0x0007 > 000C1877 66 AD lods eax, ds:[esi] > 000C1879 E8 D5 F9 call 0x000C1251 > 000C187C 83 C3 04 add bx, 0x04 > 000C187F E2 F6 loop 0x000C1877 > 000C1881 5E pop si > 000C1882 C3 ret > > NMI ... going to debugger > <...> > x86emu: SEGMASK: 0x0 > x86emu: R_DS: 0xc000 > x86emu: R_SS: 0x0 > x86emu: R_CS: 0xc000 > x86emu: R_ES: 0xc000 > x86emu: R_FS: 0x0 > x86emu: R_GS: 0x0 > x86emu: R_IP: 0x1877 > x86emu: R_SI: 0xe886 > x86emu: R_ESI: 0xe886 > x86emu: Now at 0xc1877, instruction: 0x66 > > Sometimes it's 0xc1878 or even 0xc187f. > > So, if you feel like debugging this video bios/x86 emulation mess, > feel free to contact me, I can provide you with memory dump or > disassembled memory dump.
Hmm 0x66 is used as an instruction prefix. I believe I've seen prefix-related fixes flying by on the Xorg mailing lists. Might be worth investigating whether there are any x86emu fixes that are missing from our tree.
