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    SubjectRe: [PATCH 0/3]: x86, fpu: unlazy_fpu fixes/cleanups
    On 01/29/2015 05:33 PM, Rik van Riel wrote:
    >> > Hmm, if the the thread was not using the FPU, and this fails to
    >> > save anything in to the xsave_buf, what will bndcsr point to?
    > If the thread was not using the FPU, can we reach the
    > bound range exception?
    >
    > I believe the MPX feature uses information in the xstate.

    There are really two kinds of bounds exceptions. There is an "old"
    'BOUND' instruction that will generate #BR's as well as the new MPX
    instructions. The new ones require xstate and poking the FPU, etc...
    The old one did not.

    So, we _can_ as far as I know get in to do_bounds() without using the FPU.


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