From: "Alexander van Heukelum" <heukelum@fastmail.fm>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Mark McLoughlin" <markmc@redhat.com>,
"Alexander van Heukelum" <heukelum@mailshack.com>,
"Ingo Molnar" <mingo@elte.hu>,
"Ian Campbell" <ijc@hellion.org.uk>, "Andi Kleen" <ak@suse.de>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Jeremy Fitzhardinge" <jeremy@goop.org>,
"LKML" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit
Date: Fri, 29 Feb 2008 19:56:52 +0100 [thread overview]
Message-ID: <1204311412.28554.1239873349@webmail.messagingengine.com> (raw)
In-Reply-To: <47C85294.9030902@zytor.com>
On Fri, 29 Feb 2008 10:44:36 -0800, "H. Peter Anvin" <hpa@zytor.com>
said:
> Alexander van Heukelum wrote:
> >
> > My first guess is that the BIOS data area is completely non-existent for
> > Xen.
> > Is it guaranteed that the memory is zeroed out on boot? In that case we
> > can
> > special-case it easily:
> >
> > change:
> > /* Paranoia: should never happen, but... */
> > if (lowmem >= 0x100000)
> > lowmem = 0xa0000;
> >
> > into:
> > /* Strange case, like Xen ;) */
> > if (lowmem == 0 || lowmem >= 0x100000)
> > lowmem = 0x9f000;
> >
> > Can you test that?
> >
>
> The EBDA is optional anyway; I presume it should have a zero pointer if
> it isn't present.
Correct, but the value that indicates the size of the conventional
memory
area must be set. At least on any real hardware. My guess is that both
values read as 0 on Xen, which causes 0-0x100000 to be reserved. If that
is always the case the workaround is fine, I think.
Alexander
> -hpa
--
Alexander van Heukelum
heukelum@fastmail.fm
--
http://www.fastmail.fm - mmm... Fastmail...
next prev parent reply other threads:[~2008-02-29 18:57 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-24 17:46 [PATCH] Fix alignment of early reservation for EBDA Alexander van Heukelum
2008-02-24 19:27 ` Andi Kleen
2008-02-24 19:41 ` Ingo Molnar
2008-02-24 20:53 ` Alexander van Heukelum
2008-02-25 2:18 ` H. Peter Anvin
2008-02-25 16:54 ` Alexander van Heukelum
2008-02-25 17:01 ` Ingo Molnar
2008-02-25 18:07 ` [PATCH] reserve_early end-of-conventional-memory to 1MB Alexander van Heukelum
2008-02-25 18:13 ` H. Peter Anvin
2008-02-25 19:46 ` Alexander van Heukelum
2008-02-25 21:17 ` H. Peter Anvin
2008-02-26 9:30 ` Ingo Molnar
2008-02-27 14:26 ` Andi Kleen
2008-02-27 14:38 ` [PATCH] reserve_early end-of-conventional-memory to 1MB II - some numbers to put it into perspective Andi Kleen
2008-02-27 16:44 ` H. Peter Anvin
2008-02-27 20:01 ` Alexander van Heukelum
2008-02-28 13:13 ` [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit Alexander van Heukelum
2008-02-28 13:28 ` [RFC] use realmode code to reserve end-of-conventional-memory to 1MB Alexander van Heukelum
2008-02-28 21:12 ` Ian Campbell
2008-02-28 21:14 ` H. Peter Anvin
2008-02-28 23:16 ` Ian Campbell
2008-02-29 20:00 ` Ingo Molnar
2008-03-04 11:41 ` Mark McLoughlin
2008-03-04 14:33 ` Ingo Molnar
2008-03-04 15:12 ` Ian Campbell
2008-03-04 15:13 ` Jeremy Fitzhardinge
2008-03-04 15:25 ` Ingo Molnar
2008-03-04 16:02 ` Jeremy Fitzhardinge
2008-03-04 16:15 ` Ingo Molnar
2008-03-04 16:15 ` Mark McLoughlin
2008-03-04 16:23 ` Ingo Molnar
2008-03-04 17:44 ` Jeremy Fitzhardinge
2008-03-05 15:59 ` Eduardo Habkost
2008-03-05 16:08 ` H. Peter Anvin
2008-03-05 16:53 ` Eduardo Habkost
2008-03-05 17:28 ` H. Peter Anvin
2008-03-05 17:28 ` Jeremy Fitzhardinge
2008-03-05 17:38 ` H. Peter Anvin
2008-03-05 16:38 ` Jeremy Fitzhardinge
2008-03-05 17:27 ` H. Peter Anvin
2008-02-28 21:09 ` [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit Ian Campbell
2008-02-29 11:49 ` Alexander van Heukelum
2008-02-29 17:14 ` Mark McLoughlin
2008-02-29 18:38 ` Alexander van Heukelum
2008-02-29 18:44 ` H. Peter Anvin
2008-02-29 18:56 ` Alexander van Heukelum [this message]
2008-02-29 22:06 ` Mark McLoughlin
2008-02-29 22:26 ` Alexander van Heukelum
2008-03-01 16:09 ` [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit v2 Alexander van Heukelum
2008-03-01 16:12 ` [PATCH] reserve end-of-conventional-memory to 1MB on 64-bit add-on Alexander van Heukelum
2008-03-04 11:44 ` [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit v2 Mark McLoughlin
2008-03-04 13:31 ` Alexander van Heukelum
2008-03-04 14:49 ` Ingo Molnar
2008-03-04 15:16 ` Mark McLoughlin
2008-03-04 15:24 ` Ingo Molnar
2008-03-04 15:18 ` Jeremy Fitzhardinge
2008-03-04 16:51 ` Alexander van Heukelum
2008-03-04 17:05 ` H. Peter Anvin
2008-03-04 17:11 ` Jeremy Fitzhardinge
2008-03-04 18:57 ` [PATCH] reserve end-of-conventional-memory to 1MB, 32-bit, use paravirt_enabled Alexander van Heukelum
2008-03-04 19:12 ` [PATCH] reserve end-of-conventional-memory to 1MB, 64-bit, " Alexander van Heukelum
2008-02-27 14:25 ` [PATCH] Fix alignment of early reservation for EBDA Andi Kleen
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