Re: [Qemu-devel] [PATCH v9 0/6] monitor: enable OOB by default

[Peter Xu]

On Wed, Oct 10, 2018 at 08:17:41PM -0500, Eric Blake wrote:
> On 10/10/18 7:05 PM, Peter Xu wrote:
> 
> > > other than the command line that is hanging:
> > > 
> > > /home/eblake/qemu/x86_64-softmmu/qemu-system-x86_64 -S -no-user-config
> > > -nodefaults -nographic -machine none,accel=kvm:tcg -qmp
> > > unix:/var/lib/libvirt/qemu/capabilities.monitor.sock,server,nowait 
> > > -pidfile
> > > /var/lib/libvirt/qemu/capabilities.pidfile -daemonize
> > > 
> > > And I suspect it is the -daemonize that is causing the hang I'm seeing 
> > > when
> > > run by libvirt.
> > > 
> 
> > 
> > It's very possible the daemonize thing, actually Wolfgang Bumiller has
> > posted patches to fix this up (it's not the problem of this series,
> > but it just exposed this to libvirt by the series since it only
> > happens when oob and daemonize are both enabled).  The fixes are:
> > 
> >    [PATCH v2 0/2] delay monitor iothread creation
> > 
> > Since it cannot be applied cleanly onto this series, I resolved the
> > conflicts and pushed a tree here in case you wanna try with these two
> > extra patches applied:
> > 
> >    https://github.com/xzpeter/qemu/tree/test-oob
> 
> Technically, we should apply the patches in the opposite order (Wolfgang's
> first, then yours), so that bisection does not land on a known-bad hang
> situation.

Agreed, that patch actually fixes bug of current master (current
master could possibly hit the same issue when with x-oob=on and
-daemonize), so should be applied earlier when proper.

> 
> > 
> > Please feel free to test with libvirt again with that.
> > 
> > Thanks for playing with the tree and further investigation!  I will
> > also mention this in the next version of cover letter (if there is one).
> 
> Confirmed that libvirt no longer hung with Wolfgang's patches added in.

Thanks!

-- 
Peter Xu