Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes:
> On Tue, May 23, 2017 at 11:45 PM, Babu Moger <babu.moger@xxxxxxxxxx> wrote:
>> Found this problem while enabling queued rwlock on SPARC.
>> The parameter CONFIG_CPU_BIG_ENDIAN is used to clear the
>> specific byte in qrwlock structure. Without this parameter,
>> we clear the wrong byte. Here is the code.
>>
>> static inline u8 *__qrwlock_write_byte(struct qrwlock *lock)
>> {
>> return (u8 *)lock + 3 * IS_BUILTIN(CONFIG_CPU_BIG_ENDIAN);
>> }
>>
>> Define CPU_BIG_ENDIAN for SPARC to fix it.
>
>> --- a/arch/sparc/Kconfig
>> +++ b/arch/sparc/Kconfig
>> @@ -92,6 +92,10 @@ config ARCH_DEFCONFIG
>> config ARCH_PROC_KCORE_TEXT
>> def_bool y
>>
>> +config CPU_BIG_ENDIAN
>> + bool
>> + default y if SPARC
>
> Nice catch!
>
> Traditionally, CPU_BIG_ENDIAN and CPU_LITTLE_ENDIAN were defined only on
> architectures that may support both. And it was checked in platform code
> and drivers only.
> Hence the symbol is lacking from most architectures. Heck, even
> architectures that support both may default to one endiannes, and declare
> only the symbol for the other endianness:
I guess there's a reason we can't use __BIG_ENDIAN__ / __LITTLE_ENDIAN__ ?
cheers
