Control: tag -1 + moreinfo 08.05.2013 17:30, Lisandro Damián Nicanor Pérez Meyer wrote: > Package: qemu-user-static > Version: 1.1.2+dfsg-6a > Severity: important > > Hi! I'm using qemu-mips-static to build some packages in a chroot. > Up to late last year I could do this without problems, using > a 64 bits wheezy host and a mips chroot. > > After updating the chroot to stable wheezy, I've found that running > Doxygen with dot graphs enabled will make qemu-mips-static hang the CPU.
It's interesting that you mention _chroot_ upgrade as something that caused this issue to appear, not the _host_ upgrade. So as far as I understand, it is a change in the "guest" broke existing qemu, -- usually it is exactly the opposite, qemu upgrade breaks stuff... > After further digging, I've found that using DOT_NUM_THREADS = 0 in > Doxygen's setup will use n+1 threads, where n is the number of available > processors (which, afaiu, it's the normal behaviour of doxygen). Multithreaded apps inside linux-user qemu targets (as in your case) are known to break randomly. This just become more apparent in this version of qemu - the race conditions has always been there, but now we just hit them more often. We already have a bugreport open about this. > If I set this value to match the number of processors, everything is OK. This is actually interesting. > I'm setting this bug as important as I can't even kill -9 the process and > have to reboot the host in order to get my CPU back. and this is the very important point. This is qemu-user, it does not do any fancy stuff with the host kernel (like, say, qemu-system-x86_64 -enable-kvm do) - it is regular userspace process doing the same stuff as any other regular app would do. If that causes the host kernel to not be able to release the process with kill -9, that's a big kernel issue. Please at least do a kernel stack dump (echo t > /proc/sysrq-trigger), find the process in question and post it here. It may be that this bug report needs to be reassigned to kernel instead... Thank you! /mjt -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
