[Spice-devel] [PATCH xf86-qxl] Fix crash when calling CrtcRotate()

[David Airlie]

----- Original Message -----
> From: "Rob Clark" <robdclark at gmail.com>
> To: "Marc-André Lureau" <marcandre.lureau at gmail.com>
> Cc: "Christophe Fergeau" <cfergeau at redhat.com>, "Marc-André Lureau" <marcandre.lureau at redhat.com>, "spice-devel"
> <spice-devel at lists.freedesktop.org>, airlied at redhat.com
> Sent: Friday, 10 October, 2014 5:51:28 PM
> Subject: Re: [Spice-devel] [PATCH xf86-qxl] Fix crash when calling CrtcRotate()
> 
> On Thu, Oct 9, 2014 at 12:29 PM, Marc-André Lureau
> <marcandre.lureau at gmail.com> wrote:
> > Hi
> >
> > Rob and Dave, I hope you can shed some light here.
> >
> > On Thu, Sep 18, 2014 at 1:26 PM, Christophe Fergeau <cfergeau at redhat.com>
> > wrote:
> >>
> >> A bit confused that we try to call something that cannot work in our
> >> code. Can drmmode_set_mode_major report an error rather than attempting
> >> to rotate?
> >
> >
> > It seems src/qxl_drmmode.c is based on xf86-video-modesetting code, also
> > calling CrtcRotate:
> > http://cgit.freedesktop.org/xorg/driver/xf86-video-modesetting/tree/src/drmmode_display.c
> >
> > Until very recently, it also implemented those stub functions:
> > http://cgit.freedesktop.org/xorg/driver/xf86-video-modesetting/commit/src?id=91571cce03adc58a10b5d76307629efc7c994c3e
> >
> > I wonder if xf86-video-modesetting will reach the same crash now (since it
> > also has no crtc->driverIsPerformingTransform).
> 
> So, I guess I'm missing some context here, but in xf86CrtcScreenInit()
> if those two hooks are not implemented, it should only expose support
> for zero degree rotation (ie. rotation not supported)..  what crash
> are you seeing?

I'm not near the code at the moment, but I seem to remember the X server doing something stupid like calling xf86CrtcRotate,
if the crtc won't fit in the root pixmap, so it assumes it must be rotated.

Dave.