Re: [Qemu-devel] [PULL 14/15] qemu-char: add logfile facility to all chardev backends

[Daniel P. Berrange]

On Fri, Feb 12, 2016 at 06:04:59PM +0000, Daniel P. Berrange wrote:
> On Fri, Feb 12, 2016 at 06:12:46PM +0100, Markus Armbruster wrote:
> > "Daniel P. Berrange" <address@hidden> writes:
> > 
> > > On Fri, Feb 12, 2016 at 05:49:38PM +0100, Markus Armbruster wrote:
> > >> "Daniel P. Berrange" <address@hidden> writes:
> > >> 
> > >> > On Thu, Jan 21, 2016 at 07:16:25AM +0100, Hervé Poussineau wrote:
> > >> >> Hi,
> > >> >> 
> > >> >> This patch (commit d0d7708ba29cbcc343364a46bff981e0ff88366f) 
> > >> >> regresses the following command line:
> > >> >> qemu-system-i386 -nodefaults -chardev vc,id=mon0 -mon chardev=mon0
> > >> >> 
> > >> >> Before:
> > >> >> [nothing is print on console]
> > >> >> 
> > >> >> After:
> > >> >> QEMU 2.5.50 monitor - type 'help' for more information
> > >> >> (qemu)
> > >> >> 
> > >> >> In both cases, a working vc is created in the GTK+ UI.
> > >> >> 
> > >> >> Reverting the commit (and fixing the trivial conflict) makes things
> > >> >> work again.
> > >> >
> > >> > Thanks for the heads-up, I'll investigate and submit a fix
> > >> 
> > >> For the record, it also breaks ivshmem-test when the slow tests are
> > >> included.  I'd be willing to test your fix; got a pointer for me?
> > >
> > > https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg02738.html
> > 
> > No luck.  Please try the following reproducer:
> > 
> >   $ make tests/ivshmem-test
> >   $ QTEST_QEMU_BINARY='x86_64-softmmu/qemu-system-x86_64' 
> > QTEST_QEMU_IMG=qemu-img MALLOC_PERTURB_=${MALLOC_PERTURB_:-$((RANDOM % 255 
> > + 1))} gtester -k --verbose -m slow tests/ivshmem-test
> 
> Yes, I can reproduce that. Will put it on my todo list for next week.

So I investigated this, and my commit here is not the cause. My commit
introduced a crash bug due to NULL pointer reference. This was fixed
already in by Marc-Andre in


  commit 9940c3236f318949c92099163281d5d23a9fcf4f
  Author: Marc-André Lureau <address@hidden>
  Date:   Mon Dec 21 12:10:13 2015 +0100

    ivshmem: use a single eventfd callback, get rid of CharDriver


I bisected the test failure again and found this change to blame:

  commit 428c3ece97179557f2753071fb0ca97a03437267
  Author: Stefano Stabellini <address@hidden>
  Date:   Wed Jan 13 14:59:09 2016 +0000

    fix MSI injection on Xen

which makes more sense, because the test case failure you identified
is specifically with the MSI code in ivshmem


Regards,
Daniel
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