From: Keir Fraser <keir@xensource.com>
To: Gerd Hoffmann <kraxel@suse.de>, Keir Fraser <keir@xensource.com>
Cc: Xen devel list <xen-devel@lists.xensource.com>
Subject: Re: CONFIG_XEN_COMPAT_030002 broken?
Date: Mon, 13 Nov 2006 16:56:30 +0000 [thread overview]
Message-ID: <C17E543E.46EC%keir@xensource.com> (raw)
In-Reply-To: <4558A1B3.8080409@suse.de>
On 13/11/06 16:47, "Gerd Hoffmann" <kraxel@suse.de> wrote:
>> To fix this we'd need to make all the KERNPG_XXX macros into variables and
>> poke in PAGE_USER if running on an older version of Xen.
>
> As xen must be able to deal with PAGE_USER being set anyway (to deal
> with old guests) I'd simply make that a compile time option depending on
> CONFIG_XEN_COMPAT_030002, so we can avoid the extra cost of checking
> some variable at runtime ...
>
> What was the reason for that change btw? Just make the differences
> between native and paravirtualized smaller?
Yes, and to allow fewer TLB entries to be flushed when switching between
guest kernel and guest user. That optimisation is foiled if PAGE_USER is set
everywhere.
-- Keir
next prev parent reply other threads:[~2006-11-13 16:56 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-13 10:43 CONFIG_XEN_COMPAT_030002 broken? Gerd Hoffmann
2006-11-13 16:09 ` Gerd Hoffmann
2006-11-13 16:40 ` Keir Fraser
2006-11-13 16:47 ` Gerd Hoffmann
2006-11-13 16:56 ` Keir Fraser [this message]
2006-11-13 17:08 ` Gerd Hoffmann
2006-11-13 17:12 ` Keir Fraser
2006-11-14 11:14 ` Jan Beulich
2006-11-14 11:50 ` Keir Fraser
2006-11-14 12:32 ` Jan Beulich
2006-11-14 12:42 ` Keir Fraser
2006-11-14 13:02 ` Jan Beulich
2006-11-14 13:12 ` Keir Fraser
2006-11-14 15:11 ` Gerd Hoffmann
2006-11-14 15:25 ` Keir Fraser
2006-11-14 15:35 ` Gerd Hoffmann
2006-11-14 16:06 ` Gerd Hoffmann
2006-11-14 17:01 ` Keir Fraser
2006-11-15 10:02 ` Gerd Hoffmann
2006-11-15 10:10 ` Keir Fraser
2006-11-14 15:43 ` Jan Beulich
2006-11-14 15:40 ` Jan Beulich
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