> > I don't think we can really just nuke support for them, maybe we should
> > fix the support if we can...  the problem I have is removing them will
> > signiciantly slow down a lot of working systems.. if the X server doesn't
> > do the correct thing..
>
> Problem here Dave is that there are probably a lot of systems that use
> the *fb drivers are already slower. In an *fb model in that the user
> hasn't explicitly turned off the mtrr then there's only a small range
> that will actually get configured for video memory. The DRM will already
> fail to add the correct range as the kernel will refuse to overwrite an
> existing range. You may find things speed up in many cases if we remove
> it from the DRM.


Looking at X it sets up the framebuffer mtrr for most cards, but nothing
for AGP, mtrr for AGP is as far as I know a big win as we can't cache the
aperture so write combining is needed... maybe we can stop the DRM from
allocating MTRRs for framebuffers in the DRM but leave the code in for the
AGP space... then the i915 can just turn it off in the drm and let X do
it...

We can add an option for DRM to turn on mtrr for framebuffer.. or maybe we
can check for an pre-existing and if there is one we can just do nothing,
or add one if not .. or a drm driver option to enable/disable it..

> > Well EGL would need to set it up, not the X server itself, or I suppose in
> > the case I'd like to get designed is to have the mode-setting/DRM initing
> > process to do it..
>
> My point here, being user space needs to set these up, not the kernel.

sorry was jjust me thinking out loud :-)

Dave.

-- 
David Airlie, Software Engineer
http://www.skynet.ie/~airlied / airlied at skynet.ie
Linux kernel - DRI, VAX / pam_smb / ILUG



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