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Re: [Xen-devel] Shadow Code Reorganization

To: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Shadow Code Reorganization
From: Gerd Knorr <kraxel@xxxxxxx>
Date: Wed, 27 Jul 2005 09:27:52 +0200
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Michael Vrable <mvrable@xxxxxxxxxxx>
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> Depends what you mean by "normal". The mode that we need for migration
> of a paravirtualized guest is log_dity but with refcounts in the *guest*
> pages i.e. SHM_refcounts is not set.

Ah, *that* the log_dirty option is good for.  Looked like some
performance measurement counter on a first quick look ...

> > But it's not clear to me how the transition between "normal" 
> > and "translated" shadow mode works.  Does that need support 
> > by the guest os?
> Guests typically don't make this transition -- it's currently a guest
> compile time option whether to use the paravirtualized or translated
> shadow mode interface. This isn't strictly necessary.

Ok, more general:  How does xen and/or the guest os handle the
changes in machine<=>phys mapping as they happen on
suspend/resume and migration because the guest gets a different
set of machine pages?  Especially the guest page table updates?


panic("it works"); /* avoid being flooded with debug messages */

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