Re: [Qemu-devel] patch to fix EXC_BAD_ACCESS on Mac OS X

[Peter Maydell]

On 1 February 2013 12:14, Christopher Friedt <address@hidden> wrote:
> I've been digging through a bunch of runtime errors in OS X. One of
> them was an EXC_BAD_ACCESS (segfault) caused by some code in
> main-loop.c that accessed uninitialized stack variables. Please see
> the attached patch. The problem still exists in the master branch of
> the git repository.

That struct sigaction is not used uninitialised -- we pass a
pointer to it as the third arg to sigaction(), which fills it
in for us.

OSX generally works for me, with some caveats:
 * current master doesn't compile because of a recent patch
   related to ffsl; this should be fixed soon I hope
 * running under gdb seems to cause failures which don't
   happen running not under a debugger. In particular it
   seems that sigwait() is broken by gdb (?!?) in a way that
   means it can return zero without setting *sig. A lack
   of error checking on the return value from sigaction()
   in sigfd_handler() means we then go off into the weeds.
 * for some reason sending qemu a SIGTERM doesn't cause us
   to terminate. I've had difficulty tracking down the issues
   due to the aforementioned tendency of macos gdb to bork
   signalhandling of the debuggee.

PS: you might like to read our guidelines for patch
submission; your patch failed several of them...
http://wiki.qemu.org/Contribute/SubmitAPatch

thanks
-- PMM