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Re: [PATCH 1/2] BZ#13743: PowerPC - Add a new header for platformspecific functions
On Thu, Mar 8, 2012 at 8:58 AM, Carlos O'Donell <carlos@systemhalted.org> wrote:
> On Thu, Mar 8, 2012 at 8:52 AM, Thomas Schwinge <thomas@codesourcery.com> wrote:
>> On Thu, 8 Mar 2012 06:34:57 -0500, Ulrich Drepper <drepper@gmail.com> wrote:
>>> On Wed, Mar 7, 2012 at 09:16, Steven Munroe <munroesj@linux.vnet.ibm.com> wrote:
>>> > Now if you think only PowerPC has these issue, consider all the random
>>> > attempts to use the rdtsc instruction you might have seen, and how
>>> > useful it would be to have one well defined and correct version every
>>> > one could use.
>>>
>>> If this is a fair comparison then it is also clear that this
>>> discussion is completely misplaced here. ÂSomething as trivial as
>>> rdtsc should be handled in the same way as said instruction is: in a
>>> header in gcc. ÂThis way you also reach programmers who are not using
>>> glibc Âbut instead gcc on other platforms.
>>>
>>> Since this was brought up on the glibc list I have to assume there is
>>> more to it. ÂAnd that means your argumentation is deliberately
>>> misleading.
>>
>> I also wondered about these two issues: why is this to be part of the
>> sysdeps/unix/sysv/linux/ hierarchy, given there is nothing Linux-specific
>> to it (as far as I can tell), and why is this to be in glibc at all,
>> given there is nothing libc-specific to it (as far as I can tell)? ÂI
>> likewise would assume to find such a generic ``ISA helper header'' as
>> part of the compiler itself.
>
> The IBM team have not said that it is *not* Linux specific, so we should
> ask them.
>
> There may very well be something Linux-specific, for example on HPPA
> we have a cr16 that we can use for hp-timing, but it's only usable on
> an OS that synchronizes it among all CPUs that are online. While reading
> cr16 is easy, the setup is much more difficult and not mandated by any
> ISA.
We may unintentionally be a bit nearsighted at times w/rt Linux since
that's what we develop for.
Regarding the patch which adds the instruction sequences; there isn't
anything Linux specific about it.
It could certainly go in a header located in sysdeps/powerpc/sys/.
Ryan