Re: [Xen-devel] Quick questions- Xen hypervisor

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 11:05 -0700 on 24 Jun (1308913517), Ashwini Bhat wrote:
> Thats very helpful. Would like to know where can I get hold of the
> structure(or where should I look for) of the "idle page tables" ? and also
> monitor tables.

At this point you're into things that grep or ctags can tell you. 

> Like I tried to read through the hypervisor assuming its 4 level. But after
> the second stage, I see  00000's...
> Like is it two stage or three stage. Also, if I am not wrong in
> understanding, I see that for x86_64 , the page tables are 4 stage.

Yes; that's an architectural requirement.  If you want to use 64-bit
virtual addresses you need 64-bit page tables.  

> which is to convert from pfn to mfn. Please correct me if I am wrong.

No; pagetables convert from virtual addresses to MFNs.  For HVM guests
there is a separate 'p2m' table that holds the translation from pfn to
mfn, and in some cases that's stored in 64-bit pagetable format (because
it's convenient for the shadow pagetable code and it's the format thet
NPT uses).

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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