linux-kernel - RE: PATCH: enable PAT at Pentium M 1.7 GHz

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <7E82351C108FA840AB1866AC776AEC460938F2BF@orsmsx505.amr.corp.intel.com>
Date:	Mon, 11 Aug 2008 16:29:29 -0700
From:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
To:	"H. Peter Anvin" <hpa@...or.com>, CIJOML <cijoml@...ny.cz>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>
Subject: RE: PATCH: enable PAT at Pentium M 1.7 GHz



>-----Original Message-----
>From: linux-kernel-owner@...r.kernel.org
>[mailto:linux-kernel-owner@...r.kernel.org] On Behalf Of H. Peter Anvin
>Sent: Friday, August 08, 2008 9:34 PM
>To: CIJOML
>Cc: linux-kernel@...r.kernel.org; mingo@...hat.com; tglx@...utronix.de
>Subject: Re: PATCH: enable PAT at Pentium M 1.7 GHz
>
>CIJOML wrote:
>>
>> Well the truth is, that I use this little tweak from
>2.6.26-rc and first
>> cpu having PAT was P3 XEON. And because Intel has backward
>> compatibility, it is safe to use it.
>> I don't have any problem with loosing data or any suspend/resume
>> problems with this.
>
>Sorry, it doesn't work that simple.  There are lots of errata in CPUs,
>and data loss is too critical.
>
>You're of course welcome to run whatever you want on your machine, but
>we have to be more careful.
>

Yes. I am looking through the errata list to enable PAT on known to be good CPUs.

Unfortunately, system works fine with PAT enabled may not mean much right now.
As there are really no significant users of PAT yet. We have PAT WC enabled in
The kernel and PAT APIs exported for the drivers to use. But, unless there are
very many drivers using these PAT APIs we will not really hit the erratas for
the CPUs. Even after that, erratas are like corner cases which does not really
happen very often. So, it is best to go by the published errata list and to
disable PAT where there are known problems.

Thanks,
Venki
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/