I got this "Disassembler disagrees with translator over instruction
decoding" message asking to get reported here.
What happens here is coreboot incorrectly emits a Pentium2 instruction
while I'm running qemu with a Pentium cpu. I didn't know what to expect
but got this error message, then qemu keep looping using 100% cpu.
--
Use coreboot commit 08bb837268fb6d5ce84d07c8d9fe0ef4d56ac479, build
default config which is QEMU:
coreboot$ make
...
CBFS coreboot.rom
Built emulation/qemu-i440fx (QEMU x86 i440fx/piix4)
Run this BIOS with a Pentium cpu, enabling in_asm debugging:
coreboot$ qemu-system-i386 -nographic \
-cpu pentium -d in_asm,cpu_reset \
-bios build/coreboot.rom
[...]
IN:
0x00000000fffc1728: push %ebx
0x00000000fffc1729: sub $0x8,%esp
0x00000000fffc172c: cmpl $0x0,0xd0d00
0x00000000fffc1733: mov 0x10(%esp),%ebx
0x00000000fffc1737: je 0xfffc1785
----------------
IN:
0x00000000fffc1785: add $0x8,%esp
0x00000000fffc1788: mov %ebx,%eax
0x00000000fffc178a: pop %ebx
0x00000000fffc178b: ret
----------------
IN:
0x00000000fffc1c08: mov %ebx,(%eax)
0x00000000fffc1c0a: add $0x10,%esp
0x00000000fffc1c0d: add $0x8,%esp
0x00000000fffc1c10: pop %ebx
0x00000000fffc1c11: ret
----------------
IN:
0x00000000fffc0e88: call 0xfffc17dc
----------------
IN:
0x00000000fffc17dc: sub $0x28,%esp
0x00000000fffc17df: mov $0x402,%edx
0x00000000fffc17e4: in (%dx),%al
0x00000000fffc17e5: mov %al,0x1b(%esp)
0x00000000fffc17e9: push $0xd0d04
0x00000000fffc17ee: call 0xfffc1728
----------------
IN:
0x00000000fffc17f3: add $0x10,%esp
0x00000000fffc17f6: xor %edx,%edx
0x00000000fffc17f8: cmpb $0xe9,0xf(%esp)
0x00000000fffc17fd: sete %dl
0x00000000fffc1800: mov %edx,(%eax)
0x00000000fffc1802: mov $0xfffc365f,%edx
0x00000000fffc1807: mov $0xfffc3656,%eax
0x00000000fffc180c: push $0x402
0x00000000fffc1811: cmovne %edx,%eax
Disassembler disagrees with translator over instruction decoding
Please report this to qemu-devel@nongnu.org
Triple fault
CPU Reset (CPU 0)
EAX=fffc3656 EBX=00000000 ECX=00000000 EDX=fffc365f
ESI=fffffe52 EDI=fffc01e4 EBP=000a0000 ESP=0009ff98
EIP=fffc1811 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
CS =0008 00000000 ffffffff 00cf9b00 DPL=0 CS32 [-RA]
SS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
DS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
FS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
GS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT= fffc0200 0000001f
IDT= 00000000 00000000
CR0=60000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000
DR3=0000000000000000
DR6=00000000ffff0ff0 DR7=0000000000000400
CCS=000000e9 CCD=00000016 CCO=SUBB
EFER=0000000000000000
FCW=037f FSW=0000 [ST=0] FTW=00 MXCSR=00001f80
FPR0=0000000000000000 0000 FPR1=0000000000000000 0000
FPR2=0000000000000000 0000 FPR3=0000000000000000 0000
FPR4=0000000000000000 0000 FPR5=0000000000000000 0000
FPR6=0000000000000000 0000 FPR7=0000000000000000 0000
XMM00=00000000000000000000000000000000
XMM01=00000000000000000000000000000000
XMM02=00000000000000000000000000000000
XMM03=00000000000000000000000000000000
XMM04=00000000000000000000000000000000
XMM05=00000000000000000000000000000000
XMM06=00000000000000000000000000000000
XMM07=00000000000000000000000000000000
----------------
IN:
0x00000000fffc1bf0: cmp $0x10000000,%eax
0x00000000fffc1bf5: ja 0xfffc1c12
----------------
IN:
0x00000000fffc1bf7: cmp %edx,%eax
0x00000000fffc1bf9: jne 0xfffc1c12
QEMU 2.8.1 monitor - type 'help' for more information
(qemu) q
also same with today's master 454d7dc9bc13e46084e0612076e6952c40f4afeb:
QEMU 2.9.50 monitor - type 'help' for more information
(qemu) q
in disas.c:
254 if (count < 0)
255 break;
256 if (size < count) {
257 fprintf(out,
258 "Disassembler disagrees with translator over
instruction "
259 "decoding\n"
260 "Please report this to qemu-devel@nongnu.org\n");
261 break;
262 }
263 }
This was added in commit 754d00ae3a1bfabb6069b59f72cdec1dee99ea0b from
2009 with svn message:
"Safety net for the cases where disassembler/translator disagree over
instruction decoding"
Regards,
Phil.
