[mdk-re] Fw: Re: Athlon PSE/AGP Bug

[Konstantin Volckov <goldhead@altlinux.ru>]

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Hi!

Это письмо промелькнуло сегодня в linux-kernel. Из него следует, что
проблемы с Athlon'ом возникают только при наличии видеокарты nVidia и
использовании их закрытых драйверов. Очень похоже на правду.

Begin forwarded message:

Date: Tue, 22 Jan 2002 09:05:18 +0200
From: Ville Herva <vherva@niksula.hut.fi>
To: "David S. Miller" <davem@redhat.com>
Subject: Re: Athlon PSE/AGP Bug


David S. Miller said:
>
> The funny part is, if this published errata is the problem, it cannot be
> a problem under Linux since we never invalidate 4MB pages.  We create
> them at boot time and they never change after that.

and:
>  From: Arjan van de Ven <arjanv@redhat.com>
>  > Well we don't know what nvidia's kernel module is doing.....         
>  >                                                                      
                > I know it isn't using large pages, that is for sure.

and:
> I think this is all "just so happens" personally, and all the that
> turning off the large pages really does is change the timings so that
> whatever bug is really present simply becomes a heisenbug.

Andrea Arcangeli <andrea@suse.de> said:
> My same wondering, however I wasn't sure how much the timing could
> really change to make the kernel bugs trigger.

Alan Cox said:
> That problem shouldnt be hitting Linux x86. I don't know about the
> Nvidia module but the base kernel shouldnt hit an invlpg on 4Mb pages


Here's what Ripperda of nVidia (I imagine this is the same "Terrence
Ripperda of NVIDIA" mentioned at http://www.gentoo.org/) said on nvidia @
#irc.openprojects.net:

*** ripperda (~ripperda@z06.nvidia.com) has joined channel #nvidia
<Primer> ripperda: my man!
<Primer> major props for reporting the athlon bug
<ripperda> hey primer
<ripperda> thanks, hopefully we can get athlons a lot more stable under
the drivers now
<ripperda> I feel bad I screwed the pooch and didn't get it figured out
quicker
<Thunderbird> who discovered the bug after all?
<Primer> Thunderbird: AMD, back in Sept. 2000
<Primer> :P
<ripperda> one of our main windows kernel developers here, over a year ago
<Primer> except they forgot to tell us
<Thunderbird> why did nobody publish it before then?
<ripperda> he mentioned it to me, but I was swamped with other things,
tried to see if it would affect us, but was still a little new to the
kernel code<Russ|werk> hey ripperda
<Russ|werk> ripperda: is the fix going to cause a release?
<ripperda> this athlon bug can't be fixed in our code, that's a kernel
issue

So clearly either nvidia driver uses large paging or there appears to be
some great misunderstanding.

Also, drobbins at http://www.gentoo.org goes on to say:

"I informed kernel hacker Andrew Morton of the issue; he put me in touch
with Alan Cox.  Alan is going to try to add some kind of Athlon/AGP CPU
bug detection code to the kernel so that it will be able to auto-downgrade
to 4K pages when necessary."

Another case of miscommunication?

I sincerely hope you guys can sort this out...


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-- 
Успехов,
Konstantin

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