Hi,
I install benh kernel and applied your patches on my new Powerbook Titanium.
Seems to be working, it's nice to get more than 400FPS. Unfortunately it still seems to be a bit flaky.
It does freeze the machine randomly when running GLX apps.
daRonin
From: Derrik Pates <hidden> Date: 2002-01-24 21:32:32
On Thu, 24 Jan 2002, daRonin wrote:
I install benh kernel and applied your patches on my new Powerbook Titanium.
Seems to be working, it's nice to get more than 400FPS. Unfortunately it still seems to be a bit flaky.
It does freeze the machine randomly when running GLX apps.
That's the ever-lovely UniNorth AGP adding joy to your day. Ben's still
working on getting the kinks out of supporting it - it's weird.
Derrik Pates | Sysadmin, Douglas School | #linuxOS on EFnet
dpates@dsdk12.net | District (dsdk12.net) | #linuxOS on OPN
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From: Michel Lanners <hidden> Date: 2002-01-25 04:59:32
On 24 Jan, this message from Derrik Pates echoed through cyberspace:
On Thu, 24 Jan 2002, daRonin wrote:
quoted
I install benh kernel and applied your patches on my new Powerbook Titanium.
Seems to be working, it's nice to get more than 400FPS. Unfortunately it still seems to be a bit flaky.
It does freeze the machine randomly when running GLX apps.
That's the ever-lovely UniNorth AGP adding joy to your day. Ben's still
working on getting the kinks out of supporting it - it's weird.
By chance, this would not be something comparable to what has been
discovered for the athlon processor under linux recently? Namely cache
coherency problems between processor and AGP.
From what I understood (which may be wrong ;-) AGP gart is non-coherent
(by design?) . So, if the processor has a _cacheable_ mapping for the
same memory as the AGP card also has, there can be coherency problems if
the (valid) data in the processor's cache is modified by the AGP card
before the processor writes the cache line back to memory.
It was also mentioned that the erronous behaviour was related to
speculative writes, which are also use on the PPC processors.
Just a shot in the dark...
Michel
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From: Tony 'Nicoya' Mantler <hidden> Date: 2002-01-25 07:26:08
At 10:59 PM -0600 1/24/02, Michel Lanners wrote:
[...]
By chance, this would not be something comparable to what has been
discovered for the athlon processor under linux recently? Namely cache
coherency problems between processor and AGP.
quoted
From what I understood (which may be wrong ;-) AGP gart is non-coherent
(by design?) . So, if the processor has a _cacheable_ mapping for the
same memory as the AGP card also has, there can be coherency problems if
the (valid) data in the processor's cache is modified by the AGP card
before the processor writes the cache line back to memory.
It was also mentioned that the erronous behaviour was related to
speculative writes, which are also use on the PPC processors.
Just a shot in the dark...
It's not the speculative write that kills the athlon, it's the fact that
the incomplete speculative write dirties the otherwise clean cache line,
which then gets written back unmodified somewhere down the road.
Caching non-coherent segments should be safe-ish so long as you:
1: Write a full cache line, and always a full cache line.
2: Always flush sequentially after writing.
3: Always invalidate sequentially before reading.
The athlon's speculative writes would violate rules #1 and #2. If the PPC
dirties the cache line on it's incomplete speculative writes, then it also
violates the same rules. (Does it? Anyone?)
Of course, if the code itself violates these rules, then all hell breaks
loose. :)
Indeed the simple solution is to turn off caching on AGP-mapped pages.
Cheers - Tony 'Nicoya' Mantler :)
--
Tony "Nicoya" Mantler - Renaissance Nerd Extraordinaire - nicoya@apia.dhs.org
Winnipeg, Manitoba, Canada -- http://nicoya.feline.pp.se/
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I install benh kernel and applied your patches on my new Powerbook Titanium.
Seems to be working, it's nice to get more than 400FPS. Unfortunately it still seems to be a bit flaky.
It does freeze the machine randomly when running GLX apps.
That's the ever-lovely UniNorth AGP adding joy to your day. Ben's still
working on getting the kinks out of supporting it - it's weird.
Yes, weird would describe it. After running it for a while, even without
it crashing the system, after a while the GLX libs just seem to disappear
from /usr/X11/lib/modules/extensions. No log or console messages, nothing.
Very weird...
daRonin
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