On 05/29/2014 01:36 PM, Laszlo Ersek wrote: > In this series I try to implement the ideas that (I believe) were > suggested by Gerd and Amit in > <https://bugzilla.redhat.com/show_bug.cgi?id=1080376>. > > When the guest agent exits or dies (disconnects from the virtio-serial > port), the backend (eg. a host-side unix domain socket) doesn't (in > general, can't) reflect it. This lack of info tends to trip up libvirt > in some cases, waiting indefinitely for an agent that doesn't exist. > > The series adds two monitor events that report about virtio-serial ports > being opened and closed (for online notification), and extends the > "query-chardev" QMP command's return type with a "frontend_open" bool > (for querying at late libvirt startup).
Cool! > > Admittedly, these two don't report on the same level (frontend vs. > backend), but the association is under libvirt's control, so it should > be fine, and it helps keep the series non-intrusive. (Also known as, "I > have a fleeting chance implementing it, having authored neither chardev > nor virtio-serial".) > > The series can be tested with libvirt immediately, as follows: > > 1. set up qga as usual > > 2. add the following XML element under the /domain element in the > domain config: > > <qemu:commandline > xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'> > <qemu:arg value='-global'/> > <qemu:arg value='virtserialport.report_connstate=true'/> > </qemu:commandline> > > (libvirt ignores unrecognized events, see > qemuMonitorJSONIOProcessEvent()) Actually, while libvirt.so ignores unrecognized events, libvirt-qemu.so understands them just fine! You can set up: virsh qemu-monitor-event $dom serport --no-case --regex --pretty --loop to set up a listening loop that will fire on all case-insensitive events matching the regex "serport" (basically, the two events added in this patch) that occur on $dom, until you get tired and hit Ctrl-C. > > 3. configure libvirtd to log QEMU monitor and agent traffic; > in "libvirtd.conf", set > > log_filters="1:qemu_monitor_ 1:qemu_agent" > log_outputs="1:file:/var/log/libvirt/libvirtd.log" No need to resort to log snooping when you can just use virsh :) > > 4. in the guest, start & stop the guest agent, and in lockstep: > - on the host, issue: > virsh qemu-monitor-command DOMAIN --pretty \ > '{"execute":"query-chardev"}' > > - on the host, grep the libvirtd log for the new events: > egrep 'QEMU_MONITOR_RECV_EVENT: .*VSERPORT_(DIS)?CONNECTED' \ > /var/log/libvirt/libvirtd.log > > RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1080376 > > Laszlo Ersek (2): > virtio-serial: report frontend connection state via monitor > char: report frontend open/closed state in 'query-chardev' > > qapi-schema.json | 8 +++++++- > include/monitor/monitor.h | 2 ++ > hw/char/virtio-console.c | 20 +++++++++++++++++--- > monitor.c | 2 ++ > qemu-char.c | 2 ++ > docs/qmp/qmp-events.txt | 34 ++++++++++++++++++++++++++++++++++ > qmp-commands.hx | 19 ++++++++++++++----- > 7 files changed, 78 insertions(+), 9 deletions(-) > -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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