Re: [Qemu-devel] [PULL 02/15] docs: VM Generation ID device description

[Marc-André Lureau]

Hi

On Thu, Apr 13, 2017 at 12:17 AM Ben Warren <address@hidden> wrote:

> On Apr 12, 2017, at 1:06 PM, Marc-André Lureau <address@hidden>
> wrote:
>
> +Device Usage:
> +-------------
> +
> +The device has one property, which may be only be set using the command
> line:
> +
> +  guid - sets the value of the GUID.  A special value "auto" instructs
> +         QEMU to generate a new random GUID.
> +
> +For example:
> +
> +  QEMU  -device vmgenid,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb87"
> +  QEMU  -device vmgenid,guid=auto
>
>
> The default will keep uuid to null, should it be documented? Wouldn't it
> make sense to default to auto?
>
> There is no default - you have to supply a value. It’s up to whatever
> software is managing VM lifecycle to decide what value to pass in.  Always
> setting to ‘auto’ will cause a lot of churn within Windows that may or may
> not be acceptable to your use case.
>
>
Why would you have a vmgenid device if it's always null? Does that please
some windows use-cases as well?


>
>
> +The property may be queried via QMP/HMP:
> +
> +  (QEMU) query-vm-generation-id
> +  {"return": {"guid": "324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb87"}}
> +
> +Setting of this parameter is intentionally left out from the QMP/HMP
> +interfaces.  There are no known use cases for changing the GUID once QEMU
> is
> +running, and adding this capability would greatly increase the complexity.
>
>
> Is this supposed to be not permitted?
>
> { "execute": "qom-set", "arguments": { "path":
> "/machine/peripheral-anon/device[1]", "property": "guid", "value": "auto" }
> }
>
> Is there any linux kernel support being worked on?
>
> This isn’t really relevant to the Linux kernel, at least in any way I can
> think of.  What did you have in mind?
>

Testing, but apparently we do have RFE for RHEL as Laszlo pointed out.

Thanks
-- 
Marc-André Lureau