On 21/08/12 12:47, Alexander Graf wrote: > On 08/21/2012 01:39 PM, Marc Zyngier wrote: >> On 20/08/12 21:45, Christoffer Dall wrote: >>> On Mon, Aug 20, 2012 at 1:22 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: >>>> Guys, >>>> >>>> I'm seeing weird regressions on v11 when running Thumb2 code: >>>> >>>> [ 315.637769] cyclictest (3319): undefined instruction: pc=0000a2f4 >>>> [ 315.637791] Code: 4640 4649 f002 fbc4 (ed95) 7b06 >>>> [ 316.216214] cyclictest (3324): undefined instruction: pc=0000a2f4 >>>> [ 316.217515] Code: 4640 4649 f002 fbc4 (ed95) 7b06 >>>> [ 325.854063] cyclictest (3444): undefined instruction: pc=0000a2f4 >>>> [ 325.854076] Code: 4640 4649 f002 fbc4 (ed95) 7b06 >>>> >>>> My previous work branch was quite solid (v10 based). Do we have a clear >>>> idea of what's changed in the exception handling path? Or should I >>>> consider doing the diff dance? >>>> >>>> I have the ugly feeling that we're adjusting the PC in a creative way. >>>> >>> if that's the case, it's probably the kvm_skip_instr() thingy. Which >>> code are you running? simply a Thumb guest kernel or something in user >>> space? If the latter, can you share? >> This is a Thumb2 guest + userspace guest. The instruction is always the >> same VFP instruction, so it actually looks VFP related, not PC adjusting >> as I initially thought. Doing stuff on the host seems to easily trigger >> the problem on the gust. >> >> But there's very little difference between my two trees (at least VFP >> wise), hence my growing perplexity... >> >> I'll continue investigating. > > Did you maybe compile them with different config options? Like > preemption? :) No, I'm quite careful to use the exact same config file. I also made sure I was using 3.6-rc2 for both branches. I have a few additional ARM specific patches that I'm going to back out, so the two trees are similar. Except for whatever comes from kvm/next, of course. But I can't see anything there that would have such an weird impact. M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
