Re: [Xen-devel] PAE issue (32-on-64 work)

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 19/10/06 12:18, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

>> Why not just have a fixed per-vcpu L4 and L3, into which the 4 PAE L3's
>> get copied on every cr3 load?
>> It's most analogous to what happens today.
> 
> In the shadowing (PAE, 32bit) case (a code path that, as I said, I'd rather
> see ripped out). In the general 64-bit case, this would add another
> (needless) distinct code path. I think I still like better the idea of
> clearing
> out the final 518 entries.

If we allowed non-pae-aligned L3s then you'd have no choice but to shadow
anyway, as that would be the only way to make the guest mappings appear at
the correct place in the 64-bit address space.

 -- Keir

>> We've thought of removing the page-size restriction on PAE L3's in the
>> past, but it's pretty low down the priority list as it typically doesn't
>> cost a great deal of memory.
> 
> Ah. I would have felt different.



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