Re: [Linux-fbdev-devel] Card's view of framebuffer offset i

[Petr V. <VAN...@vc...>]

On 15 Jul 02 at 4:56, Ville Syrj=E4l=E4 wrote:
> On Mon, Jul 15, 2002 at 02:02:14AM +0200, Petr Vandrovec wrote:
> > On Sun, Jul 14, 2002 at 04:10:29PM +0300, Ville Syrj=E4l=E4 wrote:
> > > Is there a way to ge the framebuffer offset to userspace? I hacked
> > > DirectFB to draw to the crtc2 display but currently I've had to hard=
code
> > > the framebuffer offset. So I need something I can feed to tmy G400.
> > 
> > In what environment? With matroxfb you have special framebuffer which
> > is displayed by CRTC2 engine.
> 
> > Offset is not explicitly exported, but
> > if you'll take low 24 bits from fb_start, you'll get offset on
> > G400/G450/G550 devices.
> 
> I don't see such a thing anywhere. Do you mean smem_start? Ok just tried
> with (smem_start + offset & 0x1ffffff) and it works for both heads. So
> that's actually 25 bits. Maybe I should just use 28 bits to accomodate
> larger framebuffers?

No. You must use exactly 25 bits on G400/G450/G550 series, because of
upper 7 bits are random: framebuffer apperture is 32MB on them, and upper
7 bits specify framebuffer position in PCI MMIO address space.
                                                Petr Vandrovec