[Xen-devel] Re: lazy context switching

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 26 Aug 2005, at 20:24, Hollis Blanchard wrote:

> However, if we ever want to context switch for other reasons (e.g. a 
> "yield"
> hypercall), we're back to the same problem: the hcall exception 
> handler won't
> save the nonvolatiles...
Instead of save/restore in just one exception handler, you could check 
a flag on the exit path of all exception handlers (maybe the same flag 
that sync_vcpu_execstate spins on). If that flag is clear you know you 
need to take a slower path that saves the non-volatiles into the old 
vcpu struct and loads from the new vcpu struct.
 -- Keir


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