Re: [Qemu-devel] [v2][PATCH 2/2] libxl: introduce gfx_passthru_kind

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-03-16 at 09:07 +0800, Chen, Tiejun wrote:
> On 2015/3/13 18:11, Ian Campbell wrote:
> > On Fri, 2015-03-13 at 09:39 +0800, Chen, Tiejun wrote:
> >>> I don't think you can abort here, since a user can set
> >>> b_info->u.hvm.gfx_passthru_kind to default. You would need to
> >>> return an error.
> >>
> >> Then, looks I should do this,
> >>
> >> LOG(ERROR, "No supported IGD to passthru," " or please force set
> >> gfx_passthru=\"igd\".\n"); return NULL;
> >
> > If I remember the context correctly this is in the autodetect case,
> > so I think shouldn't mention IGD. Something like "Unable to detect
> > graphics passthru kind, please set gfx_passthru_kind. See xl.cfg(5)
> > for more
> 
> s/gfx_passthru_kind/gfx_passthru, right? Because actually we always get
> 'gfx_passthru_kind' from 'gfx_passthru'.

I think you have it backwards.

In the case here gfx_passthru=1 has been set by the user, but
gfx_passthru_kind=DEFAULT. So libxl has tried to autodetect but it has
failed.

So if the user wants to make progress they should set gfx_passthru_kind
to whatever type of passthrough they were trying to do.

Alternatively I suppose you could recommend removing gfx_passthru=1 (or
changing to=0), but given they've set =1 that doesn't seem to be the
most productive suggestion.

Ian.