Re: [tip:x86/mce] x86/bitops: Move BIT_64() for a wider use

[Borislav Petkov]

On Wed, May 23, 2012 at 09:11:51AM -0700, H. Peter Anvin wrote:
> On 05/23/2012 09:10 AM, Peter Zijlstra wrote:
> > On Wed, 2012-05-23 at 09:07 -0700, tip-bot for Borislav Petkov wrote:
> >> +#define BIT_64(n)                      (U64_C(1) << (n))
> > 
> > Because writing 1ULL << n is too much work? 
> > 
> 
> Because writing 1ULL << n is broken in anything that needs to be used in
> assembly, for example.

Actually we need a BIT() macro that works both
on 32- and 64-bit. But that won't be that easy:
http://lkml.indiana.edu/hypermail/linux/kernel/1010.1/02335.html

And it should return UL for shift values < 32 and ULL otherwise.

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Boris.

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