From: "H. Peter Anvin" <hpa@zytor.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>,
Ian Campbell <ijc@hellion.org.uk>,
Alexander van Heukelum <heukelum@mailshack.com>,
Ingo Molnar <mingo@elte.hu>,
Alexander van Heukelum <heukelum@fastmail.fm>,
Andi Kleen <ak@suse.de>, Thomas Gleixner <tglx@linutronix.de>,
Mark McLoughlin <markmc@redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] use realmode code to reserve end-of-conventional-memory to 1MB
Date: Wed, 05 Mar 2008 09:27:20 -0800 [thread overview]
Message-ID: <47CED7F8.1060205@zytor.com> (raw)
In-Reply-To: <47CECC8D.9090507@goop.org>
Jeremy Fitzhardinge wrote:
>>
>> I am aware that it would take more work to tell all kernel code that it
>> shouldn't look for BIOS data on this region when running as a domU guest,
>> but it seems that it would be a better solution.
>
> For the moment that's true, but we should be able to release those
> pages. On the other hand, there's been talk of making Xen hand out
> memory in physically contigious 2M chunks, which means trying to unmap
> 300k won't be possible or worthwhile. I suspect real hardware will just
> waste this memory too (it won't remap that 320k of ram to somewhere
> else; it will just be shadowed) - which is nothing compared to chipsets
> which will just throw away 1G to make space for PCI...
>
Not that 384K is all that much to worry about, but you could just map
memory from 2 MB upward, and set the kernel load address to 2 MB (which
is good for performance anyway.)
There has been talk of making the default kernel load address 16 MB, to
keep the DMA zone free.
-hpa
next prev parent reply other threads:[~2008-03-05 17:32 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 [this message]
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
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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