Re: Re: changeset 13403 ...

[Gerd Hoffmann <kraxel@suse.de>]

Keir Fraser wrote:
> 
> 
> On 29/1/07 13:48, "Keir Fraser" <keir@xensource.com> wrote:
> 
>> On 29/1/07 13:40, "Gerd Hoffmann" <kraxel@suse.de> wrote:
>>
>>> Just noticed that domU kexec doesn't work any more, changeset 13403 is
>>> the culpit.  Hmm.  No, it isn't easy to work-around ...
>>>
>>> cheers,
>> Two pagetable switches in a single multicall? First switch is to a pagetable
>> which maps only the multicall structure. This small intermediate table has
>> to be mapped read-only in the original pagetables and in the final
>> pagetables, but it will only be a few pages of memory (4 in the worst case).

Helps a bit, but doesn't solve the fundamental problem that I can't use
the page tables created by the domain-builder as-is.

> Oh, it'll need a hypercall transfer page too. And it's a mmuext_op list that
> you need, not a multicall. The transfer page and mmuext_op list can be
> placed in adjacent pages so that you don't need any more intermediate
> pagetable pages.

Hmm.  hypercall transfer page?  The one with the int 82h instructions?

Is the mmuext_op list copyed over before running it?  If so, the it
should not be required to be mapped all the time, right?  In that case I
could get away with an empty page as page directory?  Or maybe even
baseptr=NULL?

cheers,
  Gerd

-- 
Gerd Hoffmann <kraxel@suse.de>