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

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Date:	Wed, 06 Aug 2008 22:57:22 +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)

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

Thanks,
Rene
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