Re: [Linux-fbdev-devel] drm_fb_helper: Impossible to change video mode

["Michel Dänzer" <michel@daenzer.net>]

On Wed, 2010-03-10 at 13:10 -0500, Alex Deucher wrote: 
> On Wed, Mar 10, 2010 at 1:05 PM, Alex Deucher <alexdeucher@gmail.com> wrote:
> > On Wed, Mar 10, 2010 at 12:42 PM, James Simmons <jsimmons@infradead.org> wrote:
> >>
> >> See my other post about what fbdev really means in its historical
> >> context. The struct fb_info really maps better to drm_crtc than to
> >> drm_framebuffer. In fact take the case of the matrox fbdev driver. It
> >> creates two framebuffer devices even tho it used one static framebuffer.
> >> What the driver does is splits the framebuffer in two and assigned each
> >> part to a CRTC.
> >
> > The only problem with that is that it eats a lot of memory for the
> > console which limits X when it starts. On cards with limited vram ,
> > you might not have enough memory left for any meaningful acceleration
> > when X starts.
> 
> It would be nice to find a way to reclaim the console memory for X,
> but I'm not sure that can be done and still provide a good way to
> provide oops support.

What do you think the average user will care about more?

      * Seeing kernel oops/panic output about once in a lifetime. 
      * Being able to start/use X in the first place and enabling it to
        use all of VRAM.

Personally, I've never even seen any kernel oops/panic output despite
numerous opportunities for that in the couple of months I've been using
KMS. But I have spent considerable time and effort trying to get rid of
the pinned fbcon BO. If the oops/panic output is the only thing
preventing that, maybe that should only be enabled via some module
option for developers.


-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer

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