Messages in this thread | | | Date | Thu, 4 Dec 2008 00:31:44 +0000 | From | Russell King <> | Subject | Re: Yet more ARM breakage in linux-next |
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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.
> > /* 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().
Sending to Nicolas.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of:
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