Re: [PATCH v2 3/3] X86, mpx: Intel MPX xstate feature definition

From: H. Peter Anvin
Date: Fri Dec 06 2013 - 12:55:37 EST

On 12/06/2013 09:35 AM, Paolo Bonzini wrote:
> Sorry for the back-and-forth, but I think this and the removal of
> XSTATE_FLEXIBLE (perhaps XSTATE_LAZY?) makes your v2 worse than v1.
> Since Peter already said the same, please undo these changes.
> Also, how is XSTATE_EAGER used? Should MPX be disabled when xsaveopt is
> disabled on the kernel command line? (Liu, how would this affect the
> KVM patches, too?)

There are two options: we could disable MPX etc. or we could force eager
saving (using xsave) even if xsaveopt is disabled. It is a hard call to
make, but I guess I'm leaning towards the latter; we could add an
"lazyxsave" option to explicitly disable all eager features if there is
use for that.


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