Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem with fpu state changes

H. Peter Anvin
2008-08-11T19:32:19Z

Ingo Molnar wrote:
> * Suresh Siddha <suresh.b.siddha@intel.com> wrote:
>
>> Reported-and-bisected-by: Wolfgang Walter <wolfgang.walter@stwm.de>
>> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
>
> no fundamental objection to the x86 bits.
>
> shouldnt this:
>
> + if (!in_interrupt())
> + return 0;
>
> just be eliminated and the cr0/TS save/restore be made unconditional?
> irq-assymetric APIs are not nice in general.
>
> Reading/setting cr0 isnt _that_ slow. (or if it is, by how much does it
> slow things down, exactly?)
>

Setting it is relatively slow. I think that's part of the reason for
special instructions to muck with the TS flag.

Reading it might be slow on obsolete processors.

-hpa