linux-kernel - Re: AGP and PAT (induced?) problem (on AMD family 6)

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Date:	Mon, 11 Aug 2008 11:46:42 +0200
From:	Rene Herman <rene.herman@...access.nl>
To:	Andreas Herrmann <andreas.herrmann3@....com>
CC:	Dave Airlie <airlied@...il.com>, Shaohua Li <shaohua.li@...el.com>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	Arjan van de Ven <arjan@...radead.org>,
	dri-users@...ts.sourceforge.net,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: AGP and PAT (induced?) problem (on AMD family 6)

<ping>

Please note this a 2.6.27 problem (given that PAT isn't enabled by 
default, not a _pure_ regression I guess, but still).

I also still don't know if you (Andreas), Dave or Yinghai should be the 
To: on this but given that you've been the only one to react at all...

On 06-08-08 22:57, Rene Herman wrote:

> On 06-08-08 15:51, Andreas Herrmann wrote:
> 
>> On Mon, Aug 04, 2008 at 06:30:32PM +0200, Rene Herman wrote:
>>> What _does_ solve this though is booting with the "nopat" command 
>>> line parameter. I'm on 2.6.26.1 and have enabled PAT for my AMD Duron 
>>> myself. With "nopat", there's no problem to be seen anymore -- 
>>> exiting X specifically is instantaneous.
>>>
>>> With or without PAT, my /proc/mtrr is always:
>>>
>>> reg00: base=0x00000000 (   0MB), size= 512MB: write-back, count=1
>>> reg01: base=0x20000000 ( 512MB), size= 256MB: write-back, count=1
>>> reg02: base=0xe8000000 (3712MB), size=  64MB: write-combining, count=1
>>>
>>> under X joined by:
>>>
>>> reg03: base=0xe4000000 (3648MB), size=  32MB: write-combining, count=2
>>
>> To get some more debug data, can you please retest with latest kernel
>> (2.6.27-rc2)
> 
> Problem present on vanilla -rc2.
> 
>> using "debugpat" kernel option and provide dmesg output
> 
> No... my kernel message buffer isn't large enough for that :-(
> 
> Right, I guess I now know where the delay is coming from. I suppose this 
> is not expected. dmesg as captured after starting X and without 
> "debugpat" at:
> 
> http://members.home.nl/rene.herman/pat/dmesg.x
> 
> Truncated dmesg with "debugpat":
> 
> http://members.home.nl/rene.herman/pat/dmesg.x.debugpat
> 
>> plus contents of <debugfs>/x86/pat_memtype_list?
> 
> Before starting X (1K):
> 
> http://members.home.nl/rene.herman/pat/pat_memtype_list.console.debugpat
> 
> After starting X (625K):
> 
> http://members.home.nl/rene.herman/pat/pat_memtype_list.x.debugpat
> 
> (This is with 64MB AGP memory)
> 
> More data:
> 
> http://members.home.nl/rene.herman/pat/config-2.6.27-rc2-current
> http://members.home.nl/rene.herman/pat/xorg.conf
> http://members.home.nl/rene.herman/pat/Xorg.0.log
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