Re: [PATCH] PowerPC - Add a faster way to read the Time Base register

[Richard Henderson <rth at twiddle dot net>]

On 02/14/2012 02:33 PM, Ryan S. Arnold wrote:
>> > Is there a good reason why you're stringify-ing this constant
>> > rather than just writing "mfspr %0, 268"?  You certainly don't
>> > want to be polluting the namespace with an unadorned "STRINGIFY".
> We didn't want a naked (non-descriptive) opcode parameter.  There must
> be a way to do this that takes the definition as a variable, like
> perhaps the following (totally untested) code:
> 
>     __asm__ volatile (                                         \
>                      "mfspr %[tb], %2\n" \
>                      : [tb]"=r" (__tb)                         \
>                      : "i" (SPRN_TBRL)  );
> 
> 

Why didn't you want this?  Certainly that's what hp-timing.h does.

And why expose SPRN_TBRL at all?  It doesn't really do the user any good.


r~