Re: [Xen-devel] context switch

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 28 Mar 2006, at 18:40, Keir Fraser wrote:

> Why is it expensive? The updates to zero only happen if the previous 
> selector value was non-zero, which is usually not the case for 64-bit 
> apps.
> Things should work okay even without the zeroing, by the way. It just 
> avoids an unnecessary failsafe callback into the guest kernel. I fixed 
> the failsafe handler for x86/64 earlier today.
We should probably just rely on the failsafe_handler actually (assuming 
it now works :-) ).
That 'slow path' will be taken so infrequently it's not worth having a 
special prepare_arch_switch() for Xen. It's really a hangover from the 
initial port from i386.
 -- Keir


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