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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Jan Beulich <jbeulich@novell.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	Xen-devel <xen-devel@lists.xensource.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Nick Piggin <nickpiggin@yahoo.com.au>
Subject: Re: [Xen-devel] [PATCH 2/2] x86: add	 pte_set_flags/clear_flags	 forpteflag manipulation
Date: Mon, 26 Jan 2009 11:54:11 -0800	[thread overview]
Message-ID: <497E14E3.2080509@goop.org> (raw)
In-Reply-To: <497D798C.76E4.0078.0@novell.com>

Jan Beulich wrote:
> Whether a pte is live doesn't matter here: If you change P on Xen, the
> frame number representation *must* change from/to PFN to/from MFN.
> In no case (other than iomem pages) is it allowed to flip just this bit.

Yes, true. Same with _PAGE_SPECIAL, which is actually flipped by code 
here.  I guess a warning here might be useful, but really the calling 
code needs to be properly disciplined; after all setting P on a swap 
entry is no fun either.

    J

      reply	other threads:[~2009-01-26 19:54 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-22 22:24 [PATCH 2/2] x86: add pte_set_flags/clear_flags for pte flag manipulation Jeremy Fitzhardinge
2009-01-23  8:14 ` [Xen-devel] [PATCH 2/2] x86: add pte_set_flags/clear_flags for pteflag manipulation Jan Beulich
2009-01-23 21:05   ` Jeremy Fitzhardinge
2009-01-26  7:51     ` [Xen-devel] [PATCH 2/2] x86: add pte_set_flags/clear_flags forpteflag manipulation Jan Beulich
2009-01-26 19:54       ` Jeremy Fitzhardinge [this message]

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