On 06/06/13 05:28, Eric Blake wrote:
On 06/05/2013 04:32 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 provided (-rtc base=$date).
It's not safe for qemu to fix it in code, it worked like that for 3 years, changing it now may break other QEMU use cases. What qemu tries to do is to fix the document:
http://lists.gnu.org/archive/html/qemu-devel/2013-05/msg04782.html
And in libvirt side, instead of reply on the qemu, this convert Unclear grammar. Not sure if you meant:
instead of replaying the value from qemu
or:
instead of relying on the value from qemu
Will use this.
but either alternative makes more sense.
s/convert/converts/
the offset returned from qemu to the offset from host UTC, by:
/* * a: the offset from qemu RTC_CHANGE event * b: The specified date (-rtc base=$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=$date) is recorded in clock's def as an internal only member (may be useful to exposed outside?).
Internal only XML tag "starttime" is introduced to not lose the domain process's starttime after libvirt restarting/reloading:
<clock offset='variable' adjustment='304' basis='utc' starttime='1370423588'/> --- src/conf/domain_conf.c | 27 +++++++++++++++++++++++---- src/conf/domain_conf.h | 3 +++ src/qemu/qemu_command.c | 3 +++ src/qemu/qemu_process.c | 13 +++++++++++++ 4 files changed, 42 insertions(+), 4 deletions(-)
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index a16ebd1..7773abf 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -96,6 +96,7 @@ typedef enum { VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES = (1<<18), VIR_DOMAIN_XML_INTERNAL_ALLOW_ROM = (1<<19), VIR_DOMAIN_XML_INTERNAL_ALLOW_BOOT = (1<<20), + VIR_DOMAIN_XML_INTERNAL_STARTTIME = (1 << 21) Please add the trailing comma, so that the next edit to this code can also be a one-liner.
+++ b/src/conf/domain_conf.h @@ -1767,6 +1767,9 @@ struct _virDomainClockDef { struct { long long adjustment; int basis; + + /* Store the start time of guest process, internal only */ + unsigned long long starttime; Might be worth mentioning how to interpret the value - is it seconds since Epoch?
Hm, just realized that "starttime" may be confused with the start time of guest process, what we want actually is the date of "-rtc base=$date". And only valid for clock.offset == VARIABLE. So I change it to "basedate", with the nits fixed: