Re: [Xen-users] Is Xen only in guests slow (tls.disabled)

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> > I don't know if it's an issue for 32-bit PAE guests running on a 64-bit
> > hypervisor, which will be allowed by 3.0.5...
>
> PAE guests on 64-bit hypervisor will not have this issue.

Thanks for clearing that up Keir, I suspected that would be the case.

I've not looked at the 32-on-64 code at all, but I've been assuming it would 
do something scary like protecting Xen by placing it outside the 32-bit 
address space (with side benefit that system calls in the guests have less 
context switching overhead relative to 64-on-64).  And that neatly fixes the 
wrap-around segmentation problem too.

So I guess that would mean that 64-bit chips are well suited for running 
32-bit domains...  and 32-bit domains are ideally suited to running on 64-bit 
Xen.  Crazy, but cool :-)

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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