Re: [Xen-devel] [PATCH 2/3] tools:libxl: Add qxl vga interface support v2

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-11-21 at 03:27 +0000, ZhouPeng wrote:
> On Mon, Nov 19, 2012 at 7:37 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Wed, 2012-10-24 at 09:06 +0100, ZhouPeng wrote:
> >
> >> >> +For B<qxl> option, the default is 128MB. If B<videoram> is set greater
> >> >> +than 128MB, it will be trimmed to 128MB; if set less than 128MB, an
> >> >> +error will be triggered.
> >> >
> >> >
> >> > Is this a fixed value in qemu, or is this something that can be changed 
> >> > via
> >> > the command-line?
> >> Can be changed.
> >>
> >> But Ian Campbell and me have talked on sth related with this
> >> closely before. And we both agree to just support the default is
> >> enough in most time. You can get it from the url below quickly, pls
> >> read from bottom up, which can save time.
> >>
> >> http://lists.xen.org/archives/html/xen-devel/2012-07/msg00098.html
> >
> > We discussed what to do if the supplied value was too small but I don't
> > recall this behaviour of clamping a value which is larger to a specific
> > value.
> 
> I think, the key idea is just to support the default for qxl (128Mib)
> in the discussion.
> videoram is not designed for qxl video ram.
> > If we reject values which are <128M, and clamp anything which is >128M
> > to 128M then what is the point of the option?
> 
> This piece of code doesn't mean to use videoram option to assign memory for 
> qxl.
> Because videoram option comes in Xen before qxl, it need to be consided here.

You mean because video_memkb is used for VGA when QXL is disabled and
QXL when it is? So the confusion here arises because this field is doing
double duty.

Perhaps it would be better to add a separate notion of qxl_memkb? The
code in libxl__build_device_model_args_new and perhaps a handful of
other places would need to account for either videoram or qxlram
depending on which was enabled (you'd probably want a helper function
for this).

Is it possible to enable both VGA and QXL for a domain?

> 
> v2 gives user the chance to assign memory for qxl.
> >
> > Ian.
> 



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