[Xen-devel] Re: sysenter/syscall support for 32-on-64 guests?

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Jan Beulich wrote:
> Since int80 cannot be directly passed to the guest (as in 32-on-32), it
> seemed reasonable to cut on the overhead of syscalls by at least
> allowing this (and syscall could also be made work now that the vdso
> stuff is unified in 2.6.25) - for obvious reasons it still goes through the
> hypervisor, but gets there faster
>   
I guess that's a reasonable point.  But it does mean that you'd need to 
separately validate a 32-bit guest on both a 32 and 64-bit hypervisor, 
which is a bit painful.  Maybe you'd need to do that anyway... (Or 
ignore 32-bit hosts.)
   J

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