Differences in bitops argument types

Differences in bitops argument types

[Jan Kara]

  Hello,

  I've just found out that operations like constant_test_bit() take pointer
of different types on different architectures. In particular, x86_64,
blackfin and frv take void * while i386, s390 and m68k take unsigned long
*. Is this intended difference? Wouldn't using void * everywhere be more
appropriate? Thanks for answer in advance.

								Honza

Re: Differences in bitops argument types

[Paul Mackerras]

Jan Kara writes:

>   I've just found out that operations like constant_test_bit() take pointer
> of different types on different architectures. In particular, x86_64,
> blackfin and frv take void * while i386, s390 and m68k take unsigned long
> *. Is this intended difference? Wouldn't using void * everywhere be more
> appropriate? Thanks for answer in advance.

A bitmap is defined to be an array of unsigned longs.  Using an array
of a smaller or longer type will give different results on big-endian
architectures.  Therefore using unsigned long * is better, because it
finds errors where callers are using an array of some other type.

Paul.