mach64 EXA bits
macallan at netbsd.org
Thu Aug 10 01:37:27 PDT 2006
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On Aug 10, 2006, at 04:13, Benjamin Herrenschmidt wrote:
>> Not sure if that's what you mean but usually the framebuffer aperture
>> offers two views to video memory and registers, one swapped one not.
> Not quite on newer chips. For example, on radeons, you have indeed 2
> apertures, though they can be individually configured for different
> swapping settings and to map the same or 2 different areas of video
> memory. It's not that clear. Also, the swapper setting has to be
> different depending on the pixel size you are accessing (no swap for
> 8bpp, 16 bits swap for 16bpp and 32 bits swap for 32bpp).
Well, the subject says mach64, not Radeon ;)
I'm clueless about Radeons but I did some hacking on mach64 chips like
Rage II, Rage Pro etc. and those are all-or-none swappers.
> The problem is that EXA might manipulate, for example, 32 bits pixmaps
> and 8 bits mask pixmaps in the same "aperture".
> I don't remember the details of how mach64 is or can be configured.
I don't think there's much configuration regarding swapping at all -
the old ATI chips only have a split swapped / non-swapper aperture ( or
rather one BE and one LE view )
> I suppose it's less flexible than radeon, in which case, we might have
> forbid EXA from directly accessing 2 pixmaps of different bit depth at
> the same time on BE, which can be done by failing in cascaded calls to
Or just make sure you use the right view for each one. Not sure if
hammering both views at (roughly) the same time would confuse the chip
- - might be worth a try but you probably don't have to.
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