Chris Lalancette wrote: > Avi Kivity wrote: > >> You mean the gcc generates wrong code? It seems fine here (though >> wonderfully obfuscated). >> >> Can you attach an objdump -Sr svm.o? Also, what gcc version are you using? >> >> > > (sending attachment in private mail, so I don't spam the whole list with 189K > of > objdump). Note that this is an objdump -Sr of the current code, with my patch > *not* applied. > > gcc is gcc-4.3.0-7 in Fedora 9. > >
It's a gcc bug. svm_set_msr() places ecx in %rsi, and consistently uses %esi to refer to the first 32 bits. But when it compiles this bit: > case MSR_K7_EVNTSEL0: > case MSR_K7_EVNTSEL1: > case MSR_K7_EVNTSEL2: > case MSR_K7_EVNTSEL3: > /* > * only support writing 0 to the performance counters for now > * to make Windows happy. Should be replaced by a real > * performance counter emulation later. > */ > if (data != 0) > goto unhandled; > break; (where MSR_K7_EVENTSEL[0123] == 0xc001000[0123]) it compiles it into > 1811: 8d 86 00 00 ff 3f lea 0x3fff0000(%rsi),%eax > 1817: 83 f8 03 cmp $0x3,%eax > 181a: 0f 87 e2 01 00 00 ja 1a02 <svm_set_msr+0x27f> Now it uses %rsi instead of %esi, and any junk in the upper bits will cause the ja to be taken. We need to get a reduced testcase to the gcc folks, this is a serious bug. Any changes in the code to work around this would be fragile. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
