On Tue, Jun 04, 2013 at 06:59:02AM -0600, Eric Blake wrote: > On 06/04/2013 05:49 AM, Osier Yang wrote: > > https://bugzilla.redhat.com/show_bug.cgi?id=964177 > > > > Though both libvirt and QEMU's document say RTC_CHANGE returns > > the offset from the host UTC, qemu actually returns the offset > > from the specified date instead when specific date is privided > > s/privided/provided/ > > > (-rtc base=$date). > > > > It's not safe for qemu to fix it in code, it worked like that > > for 3 years, changing it now may break other QEMU use cases. > > What qemu tries to do is to fix the document: > > > > http://lists.gnu.org/archive/html/qemu-devel/2013-05/msg04782.html > > > > And in libvirt side, instead of reply on the qemu, this covert > > s/covert/convert/ > > > the offset returned from qemu to the offset from host UTC, by: > > > > /* > > * a: the offset from qemu RTC_CHANGE event > > * b: The specified date (-rtc base=$date) > > * c: the host date when libvirt gets the RTC_CHANGE event > > * offset: What libvirt will report > > */ > > > > offset = a + (b - c); > > > > The specified date (-rtc base=$date) is recorded in clock's def as > > an internal only member (may be useful to exposed outside?). > > --- > > src/conf/domain_conf.h | 3 +++ > > src/qemu/qemu_command.c | 3 +++ > > src/qemu/qemu_process.c | 12 ++++++++++++ > > 3 files changed, 18 insertions(+) > > Incomplete. You need to track the start time across libvirtd restarts > (in internal XML) for this to reliably work for an event received after > a restart; you also have to cope with a libvirtd restart not finding the > field in internal XML (because the libvirtd restart was due to upgrading > libvirt in the meantime). > > > > > diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h > > index 3a71d6c..3947a56 100644 > > --- a/src/conf/domain_conf.h > > +++ b/src/conf/domain_conf.h > > @@ -1767,6 +1767,9 @@ struct _virDomainClockDef { > > struct { > > long long adjustment; > > int basis; > > + > > + /* Store the start time of guest process, internaly only */ > > Spelling; either 'internal' or 'internally' > > > + time_t starttime; > > } variable; > > > > /* Timezone name, when > > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > > index c4a162a..9254525 100644 > > --- a/src/qemu/qemu_command.c > > +++ b/src/qemu/qemu_command.c > > @@ -5518,6 +5518,9 @@ qemuBuildClockArgStr(virDomainClockDefPtr def) > > now += def->data.variable.adjustment; > > gmtime_r(&now, &nowbits); > > > > + /* Store the starttime of qemu process */ > > + def->data.variable.starttime = now; > > Is there anything we can read out of /proc/nnn for the qemu process that > would give us a more accurate start time? In fact, why not use > virProcessGetStartTime()? And if virProcessGetStartTime is reliable > across libvirtd restarts, then you might not need to store a time_t > starttime in _virDomainClockDef. It isn't the start time of the QEMU process that we care about here. The offset is relative to the timestamp specified via the -clock command line arg. So using QEMU procss startup would be wrong. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list