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Re: [Xen-ia64-devel] Re: ia64 kexec: xen -> linux

To: "Tristan Gingold" <Tristan.Gingold@xxxxxxxx>
Subject: Re: [Xen-ia64-devel] Re: ia64 kexec: xen -> linux
From: "Magnus Damm" <magnus.damm@xxxxxxxxx>
Date: Thu, 28 Sep 2006 21:34:20 +0900
Cc: "Zou, Nanhai" <nanhai.zou@xxxxxxxxx>, Horms <horms@xxxxxxxxxxxx>, Linux-IA64 <linux-ia64@xxxxxxxxxxxxxxx>, xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
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On 9/28/06, Tristan Gingold <Tristan.Gingold@xxxxxxxx> wrote:
Le Jeudi 28 Septembre 2006 03:27, Horms a écrit :
> On Wed, Sep 27, 2006 at 11:52:12AM +0200, Tristan Gingold wrote:
> > Linux and xen call efi in real mode if set_virtual_address_map fails.
> > You may add an option in both xen and linux to force calling efi in real
> > mode. This should be really simple and you will be able to make progress.
>
> Great, I will test this out and see how it goes.
>
> > The only possible drawback is performance.
>
> What kind of performance issues would you expect?
Making EFI calls in physical mode is slower: Linux must switch from and to
virtual mode.

However EFI calls are very unfrequent so the impact should be almost nul.

This makes me wonder - is it really worth having two code paths in that case?

/ magnus

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