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Re: [PATCH] memset.S and PowerPC


"Steve Munroe" <sjmunroe@us.ibm.com> writes:

> Andreas Jaeger writes:
>
>>> Please do not fix code this way.  glibc follows the GNU Coding
>>> standards and those define how comments should be done.
>
> Oops, I did not intend this as a final patch, to be integrated, but as a
> work around for David Mueller to try. The final and preferred solution is a
> bit more complicated ...

Now I see.


>>> Do you really want a nop here?
>
> I am not sure but the base code is full of comments like:
>
> /* 40th instruction from .align */
>
> Which implies that the alignment of code (within the i-cache) was
> important. While this is likely only an important issue for early (601,
> 603, ...) PowerPC processors, I wanted to avoid messing with the implied
> magic. This is not an important issue for the 64-bit PowerPC

In that case just add this as a comment along the nop (if that's the
final solution)

> implementations which I am most familiar. Perhaps Geoff remembers the
> background on this? Does this still matter for the current inventory of
> Linux/PowerPC systems in use today?
>
>>> Can you send a clean, working patch, please?
>
> I can, but do you want this patch or the more comprehensive solution that
> deals with dcbz for different cache-line sizes?

Geoff or Ulrich have the final ok here.  My personal opionion would be
the "more comprehensive" solution.  Geoff, what do you think?

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj


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