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From: ebiederm@xmission.com (Eric W. Biederman)
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Jeremy Fitzhardinge <jeremy@goop.org>, Andi Kleen <ak@suse.de>,
	Zachary Amsden <zach@vmware.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
Date: Wed, 25 Apr 2007 12:23:18 -0600	[thread overview]
Message-ID: <m1ejm8s489.fsf@ebiederm.dsl.xmission.com> (raw)
In-Reply-To: <462F9665.1090602@zytor.com> (H. Peter Anvin's message of "Wed, 25 Apr 2007 10:56:53 -0700")

"H. Peter Anvin" <hpa@zytor.com> writes:

> Eric W. Biederman wrote:
>>> This patch only affects the initial page tables, which should have been
>>> thrown out *way* long ago at this point.
>> 
>> Yes.  I noticed this was happening a few days ago.
>> I must not have mentioned it loudly enough.
>
> You mentioned the continued use of init_mm.  This is *very* different.
>
> What we're seeing here is that ON PSE-CAPABLE HARDWARE, we continue to
> not just use the init_mm page directory, but the actual page *tables*,
> which should all have been replaced with PSE large pages to begin with.

That is what I meant if not what I communicated.  If you read the code that
is exactly what it is trying to do.

> Reusing the initial page tables on non-PSE-capable hardware *sort of*
> makes sense, but his hardware should not fall in that category, I don't
> think?  (Unless it's one of these machines that fall over if you map the
> bottom 4 MB with PSE pages?)

I agree that I don't think the current behaviour makes sense.  I think
the code has accumulated so many small modifications that is very far
from making sense in the corner cases.

arch/i386 either needs to be frozen as a legacy only thing or
it needs to be cleaned up so we can continue to enhance the code.

Eric

  reply	other threads:[~2007-04-25 18:24 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-13 21:49 H. Peter Anvin
2007-04-13 22:18 ` Zachary Amsden
2007-04-13 22:26   ` H. Peter Anvin
2007-04-13 22:40     ` Zachary Amsden
2007-04-13 22:26   ` Jeremy Fitzhardinge
2007-04-25 11:48 ` Andrew Morton
2007-04-25 15:28   ` H. Peter Anvin
2007-04-25 17:50     ` Eric W. Biederman
2007-04-25 17:56       ` H. Peter Anvin
2007-04-25 18:23         ` Eric W. Biederman [this message]
2007-04-25 18:18       ` Jeremy Fitzhardinge
2007-04-25 19:01         ` Eric W. Biederman
2007-04-25 19:19           ` Jeremy Fitzhardinge
2007-04-25 22:08           ` Jeremy Fitzhardinge
2007-04-25 22:27             ` Eric W. Biederman
2007-04-25 23:08               ` Jeremy Fitzhardinge
2007-04-25 23:45                 ` Eric W. Biederman
2007-04-26  0:14                   ` Jeremy Fitzhardinge
2007-04-27  5:02                     ` Eric W. Biederman
2007-04-26  3:27                   ` Zachary Amsden

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