Re: [Qemu-devel] [PATCH 0/2 v5] Time resync support by qemu-ga

[mdroth]

On Tue, Mar 05, 2013 at 05:39:10PM +0800, Lei Li wrote:
> This patch series attempts to add time resync support
> to qemu-ga by introducing qemu-ga commands guest-get-time
> and guest-set-time.

Thanks, applied to qga branch.

> 
> Right now, when a guest is paused or migrated to a file
> then loaded from that file, the guest OS has no idea that
> there was a big gap in the time. Depending on how long the
> gap was, NTP might not be able to resynchronize the guest.
> So adding new guest-agent command that is called any time
> a guest is resumed  and which tells the guest to update its
> own wall clock time based on the information from the host
> will make it easier for a guest to resynchronize without
> waiting for NTP.
> 
> The previous RFC send for discussion and suggestion as link
> here:
> 
> http://article.gmane.org/gmane.comp.emulators.qemu/186126
> 
> The interface for these commands like:
> 
> { 'command': 'guest-get-time', 'returns': 'int' }
> 
> { 'command': 'guest-set-time', 'data': { 'time': int } }
> 
> Notes:
> For the implementition of win32-specific commands, I plan
> to send it out in another thread later.
> 
> Suggestions and comments are welcome!
> 
> Changes since v4:
>   - Fix the missing error exit pointed by Eric.
>   - Doc improvement from Eric.
> 
> Changes since v3:
>   - Doc improvement based on Eric's suggestions.
>   - Overflow check improve from Eric. 
> 
> Changes since v2:
>   - Get rid of utc-offset, and make it just pass single nanoseconds
>     relative to the Epoch in UTC/GMT according to Anthony and
>     Eric's comments.
>   - Make time argument mandatory.
>   - Fix the overflow check for year-2038 problem.
>   - Error handel improvment from Eric. 
> 
> Changes since v1:
>   - Squashed patches add support to get host time and add
>     guest-get-time command into one.
>   - Documents improvment based on the suggestions from
>     Eric and Mike.
>   - Change the name of 'HostTimeInfo' to 'TimeInfo'.
>   - Better use-case and logic for 'guest-set-time'
>     command suggested by Eric.
>   - Error handel improvment from Luiz.
> 
> Lei Li (2):
>   qga: add guest-get-time command
>   qga: add guest-set-time command
>