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From: "H. Peter Anvin" <hpa@zytor.com>
To: Chris Bainbridge <chris.bainbridge@gmail.com>, x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: set Pentium M as PAE capable
Date: Tue, 25 Feb 2014 02:45:57 -0800	[thread overview]
Message-ID: <530C7465.2080600@zytor.com> (raw)
In-Reply-To: <20140225060146.GA4339@debian.local>

On 02/24/2014 10:01 PM, Chris Bainbridge wrote:
> Pentium M is PAE capable but does not indicate so in the CPUID response.
> This is an issue now that some distributions are no longer shipping
> non-PAE kernels (those distributions no longer boot on Pentium M). This
> small patch fixes the issue by forcing the PAE capability on Pentium M.
>
> For more discussion see https://bugs.launchpad.net/baltix/+bug/930447
>

1. This patch doesn't match the discussion in the link.
2. You would have to also enable this in the cpu testing code in
    arch/x86/boot.
3. At the very least we need to print a serious warning that the CPU
    is being run outside its specifications.  I have no personal
    information about why this CPUID bit was disabled, but it could be
    that it was discovered in testing that it didn't work correctly in
    all circumstances (e.g. high temperature.)  This is very much "use
    at your own risk..."; you could get data corruption or even
    hardware damage.

    We should probably also taint the kernel.

	-hpa



  reply	other threads:[~2014-02-25 10:46 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-25  6:01 [PATCH] x86: set Pentium M as PAE capable Chris Bainbridge
2014-02-25 10:45 ` H. Peter Anvin [this message]
2014-02-25 11:35   ` Borislav Petkov
2014-02-25 12:06   ` Peter Hurley
2014-02-25 12:07   ` One Thousand Gnomes
2014-02-25 16:26   ` Dave Jones
2014-02-25 17:16     ` H. Peter Anvin
2014-02-26 12:12       ` Chris Bainbridge
2014-02-26 13:18         ` Borislav Petkov
2014-02-26 15:49           ` Dave Jones
2014-02-26 17:18             ` Borislav Petkov
2014-02-26 17:20               ` Dave Jones
2014-02-26 17:28                 ` Borislav Petkov
2014-02-28  7:30             ` Chris Bainbridge
     [not found]               ` <CAKKYfmFgVjYwvThpB0FBB+ggOwULWKLpz7ADT1eojno_KtD9yw@mail.gmail.com>
2014-02-28 14:00                 ` Chris Bainbridge
2014-03-02 20:56                   ` Andreas Mohr
2014-03-02 20:59                     ` H. Peter Anvin
2014-03-02 21:02                     ` Dave Jones
2014-03-02 21:04                       ` Borislav Petkov
2014-03-02 21:13                         ` Andreas Mohr
2014-03-02 21:42                       ` Gene Heskett
2014-03-03 12:31                         ` One Thousand Gnomes
2014-03-03  8:04                     ` Chris Bainbridge
2014-03-03 19:29                       ` Borislav Petkov
2014-03-04  5:01                         ` Chris Bainbridge
2014-03-04  5:04                           ` H. Peter Anvin
2014-03-04  6:06                             ` Chris Bainbridge
2014-03-04 10:44                               ` Borislav Petkov
2014-03-05  4:17                                 ` Chris Bainbridge
2014-03-07 11:40                                 ` [PATCH] x86: Add forcepae parameter for booting PAE kernels on PAE-disabled Pentium M Chris Bainbridge
2014-03-10 10:25                                   ` Borislav Petkov
2014-03-20 23:30                                   ` [tip:x86/cpu] x86, cpu: " tip-bot for Chris Bainbridge
2014-03-20 23:33                                   ` tip-bot for Chris Bainbridge
2014-03-20 23:30             ` [tip:x86/cpu] Rename TAINT_UNSAFE_SMP to TAINT_CPU_OUT_OF_SPEC tip-bot for Dave Jones
2014-02-26 16:46           ` [PATCH] x86: set Pentium M as PAE capable H. Peter Anvin
2014-02-26 16:44         ` Matthew Garrett
2014-02-26 16:45           ` H. Peter Anvin
2014-02-26 17:10             ` Matthew Garrett
2014-02-26 17:57               ` H. Peter Anvin
2014-03-03  0:11                 ` H. Peter Anvin
2014-03-02 19:05 Roland Kletzing

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