Comment 14 for bug 955379

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Peter Maydell (pmaydell) wrote :

I'll take the bigger usecase, please. It's pretty hard to debug race conditions that don't manifest often enough to let you do useful logging.

From the time or two I caught it hanging, it looks like qemu is sleeping in poll, and there's a zombie child process. I wonder if what's happening is that the SIGCHLD is coming in just before syscall.c executes the poll syscall, so that qemu queues the signal for delivery to the guest (but never actually delivers it) and then enters a poll syscall that won't return (because the SIGCHLD has already arrived). If so, fixing this would require the significant redesign sketched out here:
http://lists.gnu.org/archive/html/qemu-devel/2011-12/msg00384.html