Bug#726002: xserver-xorg-video-mga: Dualheading using 1.6.2 segfaults
On Fri, Oct 11, 2013 at 2:25 AM, Robert Jacobs wrote:
> The newest release of xorg removes xaa.h and xaalocal.h (and, indeed all of
> XAA). This means that the driver is built without defining HAVE_XAA_H,
> which in turn fails to compile the line in mga_storm.c:mgaAccelInit that
> ever fills the value of the function pointer RestoreAccelState. Finally,
> because this function pointer is null, in mga_driver.c:MGACrtc2FillStrip,
> it dereferences the null pointer and crashes.
This reminds me that I have a patch for some of this sitting here:
https://bugs.launchpad.net/bugs/1180986
Maybe you can take a look and possibly suggest a better patch. And
ideally Cyril's 02-* dualhead patch should go upstream, so review of
that would be welcome too.
Best regards,
Tormod
> In addition, the other two function pointers in MGACrtc2FillStrip are also
> null. The driver does technically build and run on my G450 with all three
> commented out, but causes "mouse droppings" on the second head.
>
> In the function description, it is strongly implied that this is
> compatibility code for the G400, and thus this "workaround" isn't much
> of one.
>
> In any case, without *any* functioning acceleration mechanism, the MGA
> driver is unusably slow.
>
> Best-
> - Robert Jacobs
>
Reply to: