Re: [Xen-devel] A different probklem with save/restore on C/S 14823.

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 16/4/07 18:20, "Petersson, Mats" <Mats.Petersson@xxxxxxx> wrote:

>>> I will look at it on Monday (before I update to the new
>> version, just to
>>> make sure I can reproduce it still ;-) ).
>> 
> Ok, so some further checks, and it looks like address zero (0-0xfff) is
> mapped in, read/write. I haven't looked at the page-table, just tried to
> write to the pointer that is zero and it didn't "crash".
> 
> Any thoughts on where I should head off on this for tomorrow.

What sub-arch is Xen built for (32, pae, 64)? Are you using NPT or shadow
mode? I'd suggest write a bit of code to dump %cr3, and check e.g., are you
running on the v->arch.monitor_table. Dump all entries in the top-level page
directory -- are they all populated, or is entry 0 the only lowmem one to be
populated? Dump the pagetable walk all the way down to the mapping of
address 0: what machine address is mapped there?

I.e., basically just dump some interesting stuff and let's narrow it down
from there.

 -- Keir



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