Messages in this thread | | | Date | Wed, 03 Dec 2008 22:06:16 -0500 (EST) | From | Nicolas Pitre <> | Subject | Re: Yet more ARM breakage in linux-next |
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On Thu, 4 Dec 2008, Russell King wrote:
> On Thu, Dec 04, 2008 at 09:52:44AM +1030, Rusty Russell wrote: > > On Thursday 04 December 2008 07:11:09 Andrew Morton wrote: > > > On Wed, 3 Dec 2008 19:29:05 +0000 > > > > > > Russell King <rmk+lkml@arm.linux.org.uk> wrote: > > > > This seems to be causing lots of ARM breakage: > > > > > > > > lib/find_next_bit.c:183: error: implicit declaration of function '__fls' > > > > > > > > Whoever's responsible, > > > > > > git-blame? > > > > It's me. Turns out sparc, avr32 and arm all don't define __fls in their > > asm/bitops.h, and I'm the first one to use it in generic code. > > > > But as I prepared this patch, I note that the armv5 __fls/fls is wrong: > > __fls is wrong.
__fls used to _not_ exist at all on ARM until commit 0c65f459ce.
> > /* Implement fls() in C so that 64-bit args are suitably truncated */ > > static inline int fls(int x) > > { > > return __fls(x); > > } > > > > __fls(x) returns a bit number (0-31). fls() returns 0 or bitnumber+1. > > The 'clz' instruction returns 32 for a zero input, or (31 - most significant > set bit) - which seems to work for fls() but not __fls().
... and it looks like the person who introduced the commit above didn't take into account the fact that __fls() already had another semantic in the kernel.
> Sending to Nicolas.
I queued a fix addressing both issues for RMK to merge:
http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=5339/1
Nicolas
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