[libvirt] [PATCHv5 1/3] Support clock=variable relative to localtime
Eric Blake
eblake at redhat.com
Mon Apr 2 15:08:14 UTC 2012
On 02/06/2012 06:59 AM, Philipp Hahn wrote:
> Since Xen 3.1 the clock=variable semantic is supported. In addition to
> qemu/kvm Xen also knows about a variant where the offset is relative to
> 'localtime' instead of 'utc'.
>
> Extends the libvirt structure with a flag 'basis' to specify, if the
> offset is relative to 'localtime' or 'utc'.
>
> Extends the libvirt structure with a flag 'reset' to force the reset
> behaviour of 'localtime' and 'utc'; this is needed for backward
> compatibility with previous versions of libvirt, since they report
> incorrect XML.
>
> Adapt the only user 'qemu' to the new name.
> Extend the RelaxNG schema accordingly.
> Document the new 'basis' attribute in the HTML documentation.
> Adapt test for the new attribute.
>
> +++ b/docs/formatdomain.html.in
> @@ -985,11 +985,20 @@
> <dt><code>utc</code></dt>
> <dd>
> The guest clock will always be synchronized to UTC when
> - booted</dd>
> + booted.
> + <span class="since">Since 0.9.11</span> 'utc' mode can be converted
> + to 'variable' mode, which can be controlled by using the
> + <code>adjustment</code> attribute. If the value is 'reset', the
> + conversion is never done and an error is returned. A numeric value
> + forces the conversion to 'variable' mode using the value as the
> + initial adjustment. The default is hypervisor specific.
An error is not mandatory on 'reset' unless the hypervisor doesn't
support resetting the time back to utc on each reboot.
> @@ -1000,12 +1009,15 @@
> <dt><code>variable</code></dt>
> <dd>
> The guest clock will have an arbitrary offset applied
> - relative to UTC. The delta relative to UTC is specified
> + relative to UTC or localtime, depending on the <code>basis</code>
> + attribute. The delta relative to UTC (or localtime) is specified
> in seconds, using the <code>adjustment</code> attribute.
> The guest is free to adjust the RTC over time and expect
> that it will be honoured at next reboot. This is in
As long as we're touching this, we can favor US spelling.
> - contrast to 'utc' mode, where the RTC adjustments are
> + contrast to 'utc' and 'localtime' mode, where the RTC adjustments are
> lost at each reboot. <span class="since">Since 0.7.7</span>
> + <span class="since">Since 0.9.11</span> the <code>basis</code>
> + attribute can be either 'utc' (default) or 'localtime'.
ACK, and I'm squashing the following tweak in:
diff --git i/docs/formatdomain.html.in w/docs/formatdomain.html.in
index 3ff9c28..a382d30 100644
--- i/docs/formatdomain.html.in
+++ w/docs/formatdomain.html.in
@@ -989,16 +989,19 @@
<span class="since">Since 0.9.11</span> 'utc' mode can be
converted
to 'variable' mode, which can be controlled by using the
<code>adjustment</code> attribute. If the value is 'reset', the
- conversion is never done and an error is returned. A
numeric value
+ conversion is never done (not all hypervisors can
+ synchronize to UTC on each boot; use of 'reset' will cause
+ an error on those hypervisors). A numeric value
forces the conversion to 'variable' mode using the value as the
- initial adjustment. The default is hypervisor specific.
+ initial adjustment. The default <code>adjustment</code> is
+ hypervisor specific.
</dd>
<dt><code>localtime</code></dt>
<dd>
The guest clock will be synchronized to the host's configured
timezone when booted, if any.
- <span class="since">Since 0.9.11</span> <code>adjustment</code>
- attribute (see 'utc' mode).
+ <span class="since">Since 0.9.11,</span> the
<code>adjustment</code>
+ attribute behaves the same as in 'utc' mode.
</dd>
<dt><code>timezone</code></dt>
<dd>
@@ -1013,8 +1016,9 @@
attribute. The delta relative to UTC (or localtime) is
specified
in seconds, using the <code>adjustment</code> attribute.
The guest is free to adjust the RTC over time and expect
- that it will be honoured at next reboot. This is in
- contrast to 'utc' and 'localtime' mode, where the RTC
adjustments are
+ that it will be honored at next reboot. This is in
+ contrast to 'utc' and 'localtime' mode (with the optional
+ attribute adjustment='reset'), where the RTC adjustments are
lost at each reboot. <span class="since">Since 0.7.7</span>
<span class="since">Since 0.9.11</span> the <code>basis</code>
attribute can be either 'utc' (default) or 'localtime'.
--
Eric Blake eblake at redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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