Hello, I've hit a case where QEMU hangs not responding to anything except SIGKILL. It turned out to be a SIGSEGV in vCPU thread that was lost by masking all signals.
By blocking too many signals QEMU relies on undefined behaviour that seems to work on Linux. It's documented in POSIX reference and sigprocmask(2). Indeed signalfd(2) on Linux notes that it can't be used to receive SIGSEGV and SIGFPE. It's not clear what do with SIGBUS on macOS. We can't blindly unblock it as it's used for memory preallocation. Also the RFC adds support for thread naming on macOS. Some threads (signalfd_compat and rcu_call) are created before debug-threads=on is parsed and don't get their names though. Thank you, Roman Roman Bolshakov (2): util: Implement debug-threads for macOS qemu-thread: Don't block SEGV, ILL and FPE configure | 32 ++++++++++++++++++++++++++------ qemu-options.hx | 4 ++-- util/qemu-thread-posix.c | 11 ++++++++++- 3 files changed, 38 insertions(+), 9 deletions(-) -- 2.19.1
