Re: [PATCH] FreeBSD-SA-06:14.fpu

On Monday 22 May 2006 07:51, Matthew Dillon wrote:
> :> By the way, following command could be used to check how kernel has
> :> been compiled, regarding the CPU_FXSAVE_LEAK option:
> :>
> :> objdump -x /boot/kernel/kernel | grep fpu_clean_state
> :
> :The patch looks fine to me, but can it be CPU_FXSAVE_NOLEAK ?
> :so only people know the problem will turn it on.
> :
> :David Xu
>
>     I don't think it really needs to be optioned.  Since the FPU state
>     is demand-loaded from a trap/exception anyway, a huge amount of code
>     is run in the same path that fpu_clean_state is called from.
>     fpu_clean_state itself only eats a few nanoseconds (like maybe ~1/10
>     of the time that fninit takes).
>
> 						-Matt
>
>
I personally hate to see such nasty code if my CPU does not have such a
nasty bug, I don't know if the existing code really has impact in real world.

David Xu