Re: [PATCH] x86: Extend test_and_set_bit() test_and_clean_bit() to 64 bits in X86_64

[Andi Kleen]

On Thu, May 14, 2009 at 07:16:10AM -0700, H. Peter Anvin wrote:
> Andi Kleen wrote:
> >>>
> >> The right way to do it is to pass the proper type of register.
> > 
> > For the input index register you don't actually need 64bit and for the
> > value it's typically memory anyways.
> > 
> 
> If you have a 64-bit operation you have a 64-bit index register.  And
> you need a 64-bit index for it to handle over 2^31 (since it is signed.)

Pretty much all the bit ops and a few other operations currently have
2/4GB limits on x86-64. I don't think that's going to change.

In the kernel nothing is ever that big continuously anyways.

-Andi
-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/