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Re: [Xen-devel] [PATCH] 32on64: increase size of compat argumenttranslat

To: "Ian Campbell" <ian.campbell@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] 32on64: increase size of compat argumenttranslation area to 2 pages
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Fri, 03 Jul 2009 14:31:17 +0100
Cc: keir.fraser@xxxxxxxxxxxxx
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>>> Ian Campbell <ian.campbell@xxxxxxxxxx> 03.07.09 14:54 >>>
>32on64: increase size of compat argument translation area to 2 pages.
>The existing single page is not quite large enough to translate a
>XENMEM_exchange hypercall with order=9. Since Linux uses
>MAX_CONTIG_ORDER of 9 this seems like a reasonable upper bound to
>Increasing COMPAT_ARG_XLAT_SIZE to 2 pages is sufficient to support
>order 9 exchanges. PERCPU_SHIFT must also be increased since the
>translation area is percpu.

Perhaps we should decouple this by allocating those pages as CPUs get
brought up, and just have a pointer in per-CPU storage.


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