Re: [PATCH 1/4] LOG2: Implement a general integer log2 facility in the kernel [try #4]

Kyle Moffett
2006-10-09T09:52:10Z

On Oct 09, 2006, at 04:36:12, Jan Engelhardt wrote:i
>>>> Were you planning on porting Linux to a machine with non-8-bit-
>>>> bytes any
>>>> time soon? Because there's a lot more to fix than this.
>>>
>>> I am considering the case [assuming 8-bit-byte machines] where
>>> sizeof(u32) is not 4. Though I suppose GCC will probably make a
>>> 32-bit
>>> type up if the hardware does not know one.
>>
>> If the machine has 8-bit bytes, how can sizeof(u32) be anything
>> other than 4?
>
> typedef unsigned int u32;
>
> Though this should not be seen in the linux kernel.

Well, uhh, actually...

All presently-supported architectures do exactly that. Well, some do:

typedef unsigned int __u32;
#ifdef __KERNEL__
typedef __u32 u32;
#endif

It might be possible to clean up the types.h files a bit with
something like the following in linux/types.h (nearly identical code
is found in all of the asm-*/types.h files):

typedef unsigned char __u8;
typedef signed char __s8;
typedef unsigned short __u16;
typedef signed short __s16;
typedef unsigned int __u32;
typedef signed int __s32;
#if defined(CONFIG_ARCH_HAS_64BIT_WORD)
typedef unsigned long __u64;
typedef signed long __s64;
#elif defined(__GNUC__)
__extension__ typedef unsigned long long __u64;
__extension__ typedef signed long long __s64;
#endif

#ifdef __KERNEL__
typedef __u8 u8;
typedef __s8 s8;
typedef __u16 u16;
typedef __s16 s16;
typedef __u32 u32;
typedef __s32 s32;
typedef __u64 u64;
typedef __s64 s64;
#endif

With that you could delete ~30 lines from each of the various asm-*/
types.h files in exchange for 3 lines in each of the various arch/*/
Kconfig files.

I'll try to whip up a quick patch later today if I get the time.

Cheers,
Kyle Moffett