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
WARNING: multiple messages have this Message-ID (diff)
From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Jan Beulich <jbeulich@novell.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
Ingo Molnar <mingo@elte.hu>,
Xen-devel <xen-devel@lists.xensource.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [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
next prev parent reply other threads:[~2009-01-26 19:54 UTC|newest]
Thread overview: 9+ 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 8:14 ` Jan Beulich
2009-01-23 21:05 ` [Xen-devel] " Jeremy Fitzhardinge
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 7:51 ` Jan Beulich
2009-01-26 19:54 ` Jeremy Fitzhardinge [this message]
2009-01-26 19:54 ` Jeremy Fitzhardinge
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