Andrew, On Thu, Feb 01, 2007 at 02:55:25PM -0800, Andrew Morton wrote: > On Thu, 1 Feb 2007 01:15:55 -0800 > Stephane Eranian <[EMAIL PROTECTED]> wrote: > > > Hello, > > > > On Fri, Jan 26, 2007 at 09:49:54AM -0800, H. Peter Anvin wrote: > > > > > > > >I ran into compiler warnings with the perfmon code when I tried > > > >using test() and __set_bit() on i386. > > > > > > > >For some reason, the i386 bitops functions use unsigned long * for > > > >the address whereas x86-64/ia64 use void *. > > > > > > > >I do not quite understand why such difference? > > > >Is this just for historical reasons? > > > > > > > >Thanks. > > > > > > > > > > Arguably void * is the right thing for a littleendian architecture. For > > > bigendian architectures it unfortunately matters what the chunk size is, > > > regardless of if the chunks are numbered in bigendian (reverse) or > > > littleendian (forward) order. > > > > > > > I agree with you, but i386 is definitively little endian, so here is a patch > > against 2.6.20-rc6-mm3 to make x86-64 and i386 have the same prototypes for > > bit manipulation routines. > > > > changelog: > > - change all bit manipulation inline routine to use void * as their > > address argument instead of unsigned long *. Match x86-64 > > > > signed-off-by: stephane eranian <[EMAIL PROTECTED]> > > > > --- linux-2.6.20-rc6-mm3.orig/include/asm-i386/bitops.h 2007-01-31 > > 09:24:21.000000000 -0800 > > +++ linux-2.6.20-rc6-mm3.base/include/asm-i386/bitops.h 2007-01-31 > > 09:31:46.000000000 -0800 > > @@ -33,7 +33,7 @@ > > * Note that @nr may be almost arbitrarily large; this function is not > > * restricted to acting on a single-word quantity. > > */ > > -static inline void set_bit(int nr, volatile unsigned long * addr) > > +static inline void set_bit(int nr, volatile void * addr) > > These bitops are only valid on long*'s. Or a least, they require a > long-aligned address, and using long* is how we communicate and enforce > that. > Yes, I realize this now.
> Numerous architectures implement these functions using ulong*. If we make > this change, we risk someone doing set_bit() on, say, a char *. That > change would compile and run happily on x86 and would then fail on, say, > arm or h8/300. > > So I'd say that x86_64 is wrong, and should be changed to take ulong*. We need to fix x86-64 and also ia64 it seems. I'll see if I can do that. Thanks. -- -Stephane - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
