Re: [Xen-devel] pagetable handling in xen

[Steven Hand <Steven.Hand@xxxxxxxxxxxx>]

> On Mon, 24 Oct 2005, Aaron J. Marks wrote:
> 
> > i'm trying to understand how xen handles pagetables, but i'm a bit
> > confused:
> >
> > 1. where is a new domain's memory mapping initialized in xen?
> > 2. what're the differences between idle_pg_table and linear_pg_table and
> > are they indexed by guest linear page #s or hardware page #s?
> > 3. [this is more of an affirmation, than a question] xen can't arbitrarily
> > access *any* physical page because it doesn't map all of physical
> > memory (eg, like linux does from PAGE_OFFSET)?
> 
> okay, after staring at the code for a while (too long), i think i
> understand 1 & 2. however, i'm still uncertain about #3.
> 
> i'd like to be able to iterate over every page table of every domain from
> *within* xen. is this possible? i guess the basic mechanism that i need is
> to be able to temporarily map a domain's machine pages into xen address
> space, do the traversal, then unmap (and repeat for each domain).

Yes (at least if you're talking about 32 bit). 

Take a look at the functions map_domain_page() and unmap_domain_page()
in xen/arch/x86/x86_32/domain_page.c


cheers,

S.


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