On 04/18/2018 01:30 PM, Daniel P. Berrangé wrote: > When the agent code was first introduced back in > > commit c160ce3316852a797d7b06b4ee101233866e69a9 > Author: Daniel P. Berrange <berrange@xxxxxxxxxx> > Date: Wed Oct 5 18:31:54 2011 +0100 > > QEMU guest agent support > > there was code that would loop and retry the connection when opening > the agent socket. At this time, the only thing done in between the > opening of the monitor socket & opening of the agent socket was a > call to set the monitor capabilities. This was a no-op on non-QMP > versions, so in theory there could be a race which let us connect > to the monitor while the agent socket was still not created by QEMU. > > In the modern world, however, we long ago mandated the use of QMP > for managing QEMU, so we're guaranteed to have a set capabilities > QMP call. Once we've seen a reply to this, we're guaranteed that > QEMU has fully initialized all backends and is in its event loop. > > We can thus be sure the QEMU agent socket is present and don't need > to retry connections to it, even without having the chardev FD passing > feature. > > Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx> > --- > src/qemu/qemu_agent.c | 84 +++++---------------------------------------------- > 1 file changed, 7 insertions(+), 77 deletions(-) > Reviewed-by: John Ferlan <jferlan@xxxxxxxxxx> John -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
