Status of shadow page tables on 32bit x86

Status of shadow page tables on 32bit x86

[Arne Mejlholm]

Dear all,

I'm trying, without much success, to figure out what the status is on 
shadow page tables. Specifically
I'm interested in using fully translated/external shadow page tables. 
Referring to [1]
it seems that, as 32bit x86 non-pae still uses shadow32.c, shadow.c is 
not quite ready for 32bit. Furthermore
I assume that shadow32.c only supports shadow page tables that are 
located in the individual VMs and are
maintained by the guest OSes. Can anyone confirm this or elaborate on 
when a working version of external
shadow page tables in shadow.c can be expected in a 32bit version?

If I try to force a build of shadow.c and corresponding files (by 
explicitely saying so in the xen/arch/x86/Makefile),
I get a load of compile errors. Is there a more better and elegant way 
to do this?

Furthermore [2] suggested the possibility of an upcomming paper on 
shadow page tables, is there any update on this?
Also I would value, if any exists, pointers (besides the migration 
article) to any documentation on the
implementation of shadow page tables.

Any help is greatly appreciated.

Best Regards,
Arne Mejlholm

[1]: 
http://lists.xensource.com/archives/html/xen-devel/2005-07/msg00699.html
[2]: 
http://lists.xensource.com/archives/html/xen-devel/2005-02/msg00830.html

Re: Status of shadow page tables on 32bit x86

[Keir Fraser]

On 8 Mar 2006, at 10:07, Arne Mejlholm wrote:

> I'm trying, without much success, to figure out what the status is on 
> shadow page tables. Specifically
> I'm interested in using fully translated/external shadow page tables. 
> Referring to [1]
> it seems that, as 32bit x86 non-pae still uses shadow32.c, shadow.c is 
> not quite ready for 32bit. Furthermore
> I assume that shadow32.c only supports shadow page tables that are 
> located in the individual VMs and are
> maintained by the guest OSes. Can anyone confirm this or elaborate on 
> when a working version of external
> shadow page tables in shadow.c can be expected in a 32bit version?

shadow32.c already supports fully translated and external pagetables.

  -- Keir