Re: [Xen-devel] new domain builder breaks compatibility

[Gerd Hoffmann <kraxel@xxxxxxx>]

John Levon wrote:
> On Thu, Feb 01, 2007 at 10:04:43AM +0100, Gerd Hoffmann wrote:
> 
>> John Levon wrote:
>>> To quote xen.h:
>>>
>>> 495  *  9. There is guaranteed to be at least 512kB padding after the final
>>> 496  *     bootstrap element. If necessary, the bootstrap virtual region is
>>> 497  *     extended by an extra 4MB to ensure this.
>>> which, predictably enough, breaks Solaris, which tries to use this area as
>>> ecratch memory during early boot.
>> The attached patch should fix this.
> 
> Does that ensure the 4Mb alignment too?

Yes.  Uhm, no, depends.  It completely fills the topmost L1 pagetable
with entries, so you end up with an 4MB alignment for 32bit and 2MB
alignment for PAE and 64bit.  I think the old builder had the same
behaviour, so the 4MB are actually a documentation bug ;)

> BTW what is dom->extra_pages intended for?

Allows allocation of some extra space.  Used by the kexec bits I have in
the queue, it places some code which finishes the memory layout before
jumping to the new kernel entry point above the boot stack, so it needs
some way to reserve memory there.

cheers,
  Gerd

-- 
Gerd Hoffmann <kraxel@xxxxxxx>

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