[Nouveau] Framebuffer double buffering (via FBIOPAN_DISPLAY)

[Ilia Mirkin]

Try booting with drm_kms_helper.drm_fbdev_overalloc=200 and see if it
works with that. (There's also CONFIG_DRM_FBDEV_OVERALLOC which sets
the default.)

Cheers,

  -ilia

On Sun, Jul 5, 2020 at 3:41 PM <michael at michaelkloos.com> wrote:
>
> I am not familiar with that setting, but I have really struggled to find documentation on dealing with the framebuffer.  Referring to this guide, "http://betteros.org/tut/graphics1.php#doublebuffer", I attempted to set the mmap allocation size to double, but it caused the mmap to fail.  I no longer believe that it is a driver issue, though, because I just tried it again on a dell laptop with Intel HD Graphics 4400 to the same failure.
>
> On Jul 5, 2020 12:35, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>
> Are you setting the overallocation to 200?
>
> On Sun, Jul 5, 2020 at 3:41 AM Michael T. Kloos
> <michael at michaelkloos.com> wrote:
> >
> > Does NOUVEAU support mmaping a double-sized Framebuffer?
> > When attempting to run, where fd refers to "/dev/fb0":
> >
> > mmap(ptr, screensize * 2, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
> >
> > I get back an invalid argument error.  This doesn't happen if I only
> > request a single screensize.  Is this a limitation of the driver?
> >
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>
>