Re: [Qemu-devel] [PATCH 0/2] Remove hardcoded xen-platform device initialization (v4)

[Laszlo Ersek <lersek@redhat.com>]

On 06/18/13 15:01, Michael S. Tsirkin wrote:
> On Tue, Jun 18, 2013 at 12:57:54PM +0000, Paul Durrant wrote:
>>> -----Original Message-----
>>> From: Michael S. Tsirkin [mailto:mst@redhat.com]
>>> Sent: 18 June 2013 13:52
>>> To: Laszlo Ersek
>>> Cc: Paul Durrant; qemu-devel@nongnu.org
>>> Subject: Re: [Qemu-devel] [PATCH 0/2] Remove hardcoded xen-platform
>>> device initialization (v4)
>>>
>>> On Tue, Jun 18, 2013 at 02:37:58PM +0200, Laszlo Ersek wrote:
>>>> Hi Paul,
>>>>
>>>> (xen-devel snipped)
>>>>
>>>> On 06/18/13 13:16, Paul Durrant wrote:
>>>>> Because of concerns over backwards compatibility and a suggestion that
>>>>> xenfv should be retired in favour of using the pc machine type I have re-
>>>>> worked my original patch into 2 patches:
>>>>>
>>>>> [PATCH 1/2] Allow use of pc machine type (accel=xen) for Xen HVM
>>>>> [PATCH 2/2] Move hardcoded initialization of xen-platform device.
>>>>>
>>>>> Application of both these patches allows alternative pc machine types to
>>> be
>>>>> used with the accel=xen option, but preserves the hardcoded creation of
>>>>> the xen-platform device only for machine type xenfv.
>>>>>
>>>>> v3:
>>>>> - Add test for xen_enabled() that went missing in v2
>>>>>
>>>>> v4:
>>>>> - Remove erroneous whitespace hunk
>>>>> - Replace hw_error() with fprintf()+exit(1)
>>>>> - Add braces to single-line if
>>>>
>>>> can you please offer an opinion in the
>>>>
>>>>   [PATCH 1/2] pvpanic: initialization cleanup
>>>>   http://thread.gmane.org/gmane.comp.emulators.qemu/216940
>>>>
>>>> thread?
>>>>
>>>> >From where I stand (which is "quite afar" :)) this series of yours seems
>>>> somewhat related to my doubt there.
>>>>
>>>> Thanks!
>>>> Laszlo
>>>
>>> OK will make it skip fwcfg as we did earlier.
>>> Thanks for the review.
>>>
>>
>> Yes, I think the assert(fw_cfg) would be problematic in the xen case where, up until my patch, machine types was necessarily xenfv.
>>
>>   Paul
> 
> Do you guys actually need the pvpanic device?
> How do you know which port to use without fwcfg?

Xen domains don't know the port and don't use the pvpanic device, but
qemu starts at least. In other words, the pvpanic device is created, but
unreachable. Maybe the has_pvpanic logic should depend on (or extended
with) !xen_enabled().

Just a guess.

Laszlo