Re: [Xen-devel] Shadow Code Reorganization

Gerd Knorr
Wed, 27 Jul 2005 07:27:52 -0000

Hi,

> 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?

  Gerd

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