linux-kernel - Re: [PATCH] x86: Construct 32 bit boot time page tables in native format.

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Message-Id: <200801282302.51796.rjw@sisk.pl>
Date:	Mon, 28 Jan 2008 23:02:50 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Jeremy Fitzhardinge <jeremy@...p.org>, Pavel Machek <pavel@....cz>,
	Ingo Molnar <mingo@...e.hu>, Ian Campbell <ijc@...lion.org.uk>,
	Mika Penttilä <mika.penttila@...umbus.fi>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH] x86: Construct 32 bit boot time page tables in native format.

On Monday, 28 of January 2008, H. Peter Anvin wrote:
> Rafael J. Wysocki wrote:
> > On Monday, 28 of January 2008, Jeremy Fitzhardinge wrote:
> >> Rafael J. Wysocki wrote:
> >>> Actually, no.  We only do that with the kernel code mapping which should be
> >>> safe as long as TLBs are not flushed (and they aren't).
> >>>   
> >> Er, what?  Assuming the TLB will retain some mappings while you 
> >> overwrite the pagetable is a highly dubious prospect.  Are you copying 
> >> the same values over, or something else?
> > 
> > As long as a relocatable kernel is not used to restore a non-relocatable one
> > (or vice versa), we're copying the same values over.
> > 
> 
> So that case is deliberately considered broken?

Not deliberately, but the fix I had caused a regression.  It's just a pending
issue.

Rafael
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