Messages in this thread | | | Date | Wed, 22 Apr 2009 16:59:23 -0400 (EDT) | From | Christoph Lameter <> | Subject | Re: [RFC] __ffs64() |
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On Wed, 22 Apr 2009, Steven Whitehouse wrote:
> I'd like to add a new bitop, __ffs64() which I need in order to fix a > bug in GFS2. The question is, where should it go?
I think the location is right.
> On 64 bit arches, __ffs64() would be a synonym for __ffs(), but on 32 > bit arches it degenerates to a conditional plus a call to __ffs(). I'm > assuming that there would not be a lot of point in optimising this > operation on 32 bit arches even if such an instruction was available, so > that I should do something like the below patch. > > Does that seem reasonable, or should I give it a separate header file > under asm-generic/bitops/ like some of the similar operations? It looks > like I'd have to touch a lot of other files if I were to go that route,
One issue may be that some 32 bit architectures have a better way of doing 64 bit ffs.
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