No cache control on ppc??
Hi again,
this is more a powerpc hardware issue, but maybe there's someone her who
can shed some light on this. (hi, benh!)
Any other place to post this?
While writing a script that checks for some system properties that might
decrease video performance, I found that I'm missing one feature on ppc
kernels:
On i586 (or newer) machines with AGP, the X server can set some MTRR
ranges. AFAIUI, these tell the (CPU-internal) cache controller not to
cache video memory (which wouln't make any sense, as that is used
write-only).
While working with xine, we found that not setting these (usually because
the kernel doesn't have MTRR support) slows video playback down,
probalby due to "cache pollution". MTRR support works like "releasing the
hand brake" here...
Okay, that was the intel world.
I haven't found anything similar in powerpc kernels, so I assume there is
nothing like this. Is that correct?
If so, is that a hardware restriction?
Does the hardware do this automagically?
At least on my iBook, lspci claims that the Rage Mobility is connected via
AGP 2x, so this could be relevant.
xine can play DVDs fine on a PII-450, so why shouldn't it on a G3-600...
Cheers,
Siggi
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