Re: [Xen-devel] Re: HYBRID: gnttab_map() to map shared frames..

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Thu, 20 Oct 2011 11:39:12 +0100
Tim Deegan <tim@xxxxxxx> wrote:

> At 19:29 -0700 on 19 Oct (1319052558), Mukesh Rathor wrote:
> > > What about using PFNs from right at the top, i.e. right up near
> > > 0xffffffff? I don't think there's any particular reason these
> > > special PFNs need to be contiguous with the "regular" ones. This
> > > would limit the total amount of RAM you could give a hybrid
> > > guest, but not by much.
> > 
> > Yeah, I dinkered around a bit with e820 and realized it would be
> > migration headache, so just decided to do this. I allocate pfn's
> > near 0xffffffff and map it. Things are fine, I see all page table
> > entries just fine, the entry is put into the p2m also via
> > ept_set_entry, but for some reason it's taking fault on accessing
> > shared[0] with error code 0xb that doesn't make sense. Even the mfn
> > in xen is writable page. 
> > 
> > PGD 77895067 PUD 77896067 PMD 77897067 PTE 80000ffffffdf063
> 
> 0xB means you've got a reserved bit set.  Is 0xfff_fffdf000 above the 
> number of supported addressing bits on your CPU, by any chance?
> 
> Cheers,
> 
> Tim

Ooops, forgot to PAGE_SHIFT..  got that working now...

thanks,
mukesh

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