Messages in this thread | | | From | Christopher Friedt <> | Date | Mon, 30 Jun 2014 08:25:40 -0400 | Subject | Re: [PATCH 1/1] drm/vmwgfx: correct fb_fix_screeninfo.line_length |
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On Mon, Jun 30, 2014 at 7:48 AM, Thomas Hellstrom <thellstrom@vmware.com> wrote: > I don't think we can blame video-vmware for this. A kernel driver change > that breaks existing user-space is by definition a kernel driver bug, > regardless whether exisiting user-space is doing something horrendously > stupid.
I wouldn't be so quick to say it's a kernel bug. The fbdev contract hasn't changed. Also xf86-video-vmware isn't using the fbdev driver, and the fbdev driver code is obviously correct (see screenshots in link submitted with initial patch).
> So the fix must IMO be a kernel driver fix. My initial guess is that > once we set the bytes per line register, it might not be automatically > updated when the screen width is changed, but the documentation is poor. > I see if I can shed some light over this.
Having dumped all of the svga registers while hacking on vmwgfx, I noticed that the BYTES_PER_LINE field is initially incorrectly set to something way off. My initial reaction is that video-vmware doesn't properly compute the bytes-per-line register, and therefore that it is a video-vmware bug that has always existed.
I'm reproducing the problem and providing a fix for video-vmware as I write this.
C
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