Re: [Qemu-devel] [RFC PATCH 0/3] Time resync support by qemu-ga

[Eric Blake]

On 01/06/2013 03:06 AM, 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.
> 

> 
> The interface for these commands like:
> 
> { 'command': 'guest-get-time', 'returns': 'HostTimeInfo' }
> 
> { 'command': 'guest-set-time',
>   'data': { '*seconds': 'int', '*microseconds': 'int',
>             '*utc-offset': 'int' } }

Why are these fields marked optional?  I guess I'll find out in the
actual patch, but at first glance, I think all three would be mandatory.

> 
> TODO:
> This is a RFC version with POSIX-specific command implemented.
> I just test on Linux guest, will add win32-specific command to
> support Windows guest later. Since I want to make sure if this
> seems like the way we should be headed.

I hope that you just meant that you are lacking a win32 implementation
of the command, but that when it is implemented, it will still use the
same interface.  That is, even though windows itself doesn't use POSIX
time, and has a different Epoch than Jan 1 1970, such differences should
be transparent to the user, who should always pass a POSIX timestamp
through the interface.  What we don't want is two different commands,
where the management app then has to know whether the guest is Unix or
Windows based, to know which of the two commands to send.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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