[libvirt] [Xen-devel] [PATCH v2] libxl: Implement basic video device selection
Stefan Bader
stefan.bader at canonical.com
Fri Apr 4 10:34:22 UTC 2014
On 04.04.2014 12:31, Stefan Bader wrote:
> On 04.04.2014 11:48, Ian Campbell wrote:
>> On Fri, 2014-04-04 at 11:36 +0200, Stefan Bader wrote:
>>> + /*
>>> + * Take the first defined video device (graphics card) to display
>>> + * on the first graphics device (display).
>>> + * Right now only type and vram info is used and anything beside
>>> + * type xen and vga is mapped to cirrus.
>>> + */
>>> + if (def->nvideos) {
>>> + unsigned int min_vram = 8 * 1024;
>>> +
>>> + switch (def->videos[0]->type) {
>>> + case VIR_DOMAIN_VIDEO_TYPE_VGA:
>>> + case VIR_DOMAIN_VIDEO_TYPE_XEN:
>>> + b_info->u.hvm.vga.kind = LIBXL_VGA_INTERFACE_TYPE_STD;
>>> + /*
>>> + * Libxl enforces a minimal VRAM size of 8M when using
>>> + * LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL or
>>> + * 16M for LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN.
>>> + * Avoid build failures and go with the minimum if less
>>> + * is specified.
>>
>> Build failures? Do you mean "domain build" rather than "libvirt build"?
>>
>> I'm not sure about this fixing up the GIGO from the user side, but
>> that's a libvirt policy decision I suppose? If it were me I would just
>> let libxl provide the error and expect people to fix their domain config
>> rather than silently giving them something other than what they asked
>> for. What if increasing the VRAM causes a cascading failure due e.g. to
>> lack of memory? That's going to be tricky to debug I think!
>
> In the end its a start a domain with such a config. Which seems to be what I
*sigh* That wasn't much better English. Yes, I meant a domain build or a failure
to start a domain...
> would end up with in my testing with an admittedly older version of virt-manager
> connecting to a libvirtd running an initial version of this patch without that part.
> The error seen on the front-end was something along the lines of "failed to get
> enough memory to start the guest" (the libxl log on the other side had the
> better error message). And the gui always reduces the memory below the minimum
> for both the options (VGA and "Xen").
> That is the reason I went for "meh, go for the minimum anyways".
>
> And btw, it is already confusing enough as with cirrus, I get a 9M by default
> which is passed on to qemu on the command line and then ignored by it and one
> gets 32M in any way...
>
> -Stefan
>
>>
>>
>
>
>
>
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>
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