[PATCH 5/6] powerpc/boot: Add mfdcrx

[Segher Boessenkool]

>>> +#define mfdcrx(rn) \
>>> +	({	\
>>> +		unsigned long rval; \
>>> +		asm volatile("mfdcrx %0,%1" : "=r"(rval) : "g"(rn)); \
>>> +		rval; \
>>> +	})
>>
>> "g" is never correct on PowerPC, you want "r" here.  You can write
>> this as a static inline btw, you only need the #define stuff when
>> there is an "i" constraint involved.
>
> I think you can still use static inlines even when a
> constraint is one that requires a compile time constant.

Marking a function inline does not guarantee the compiler will
perform inline substitution on it, which you need here.  I don't
think it's a problem with recent GCC in the context of the Linux
kernel though, if you use __always_inline that is.


Segher