qemu all apps crash on OS X 10.6.8

[Eric Blair]

qemu-2.0.0-rc0 (and 1.7.1) crashes with SIGABORT in all apps when configured with --with-coroutine=sigaltstack (which is what configure selects by default) but all run fine if configured with --with-coroutine=gthread.

Crash is at line 253 (last line of Coroutine *qemu_coroutine_new(void)) in coroutine-sigaltstack.c in 2.0.0-rc0 tarball.

Platform is OS X 10.6.8 (Darwin Kernel Version 10.8.0), compiler gcc 4.2.1

Sorry for the sparse report but I'm short on time today.

[Peter Maydell (pmaydell)]

My test system is OS X 10.8.5 built with clang "Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)", and QEMU works fine there, which suggests a problem either with that version of GCC or that version of MacOSX.

You might try building with clang rather than gcc; otherwise since I don't have a system to reproduce on (or indeed much interest in tracking down bugs in old versions of MacOS, to be honest) I'm afraid you'll have to investigate this bug yourself if you want a fix for it.

[Eric Blair (qg7nvabbzvbr)]

I'm not personally worried about a fix for this, I reported it primarily for the benefit of others/the quality of the codebase as a whole. As I said, I got it working with gthreads as the coroutine provider so it's working for my needs.

Although this seems on the surface to be a problem with the specific platform versions involved it's always possible that this sheds light on something that is either an undiscovered problem on more recent platform versions or will become a problem.

It's notable that the version of xcode (and hence gcc) involved is the last from Apple with PPC support. It's precisely why I'm using it and it's precisely why someone who's targeting multiple platforms might be using it and qemu in concert.

It's possible that a fix might be to get configure to select gthreads support for OS X platforms below a certain compiler or OS version, or it may be a deeper issue.

[Peter Maydell (pmaydell)]

Unfortunately the gthreads backend is pretty strongly disrecommended -- it is really mostly there as a debug convenience when working with the block code, as there are some bad interactions between signal masking and coroutine switches that mean it's likely to cause problems when using QEMU proper.

[Thomas Huth (th-huth)]

Triaging old bug tickets... can you still reproduce this issue with the latest version of QEMU? Or could we close this ticket nowadays?

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]