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Re: [PATCH 1/2] BZ#13743: PowerPC - Add a new header for platformspecific functions
On Thu, 2012-03-08 at 11:23 -0500, Carlos O'Donell wrote:
> On Thu, Mar 8, 2012 at 11:25 AM, Steven Munroe
> <munroesj@linux.vnet.ibm.com> wrote:
> > The timebnase is just one example we are working more.
> >
> > The timebase is not a linux specific feature but other OSes do proved
> > simple C/C++ access to the timebase via headers.
> >
> > Other examples like program priority register and priority adjustment
> > ops do need to be coordinated with the kernel (PPC save/restore).
> >
> > We could split the Linux specific from the platform general cases. But I
> > don't why we would need to make this complicated.
>
> This isn't really that complicated.
>
> There is value in discussing what would be most useful to your users.
>
> > If you really insist we could have ./sys/platform.h
> > from ./sysdeps/powerpc/ that includes ./bits/platform.h from
> > sysdeps/unix/sysv/linux/
>
> That would be optimal, and doesn't violate the layering principle
> we have in glibc.
>
> >> Regarding the GCC vs. GLIBC header split decision, I've summarized my
> >> opinion, and the points made in this conversation so far:
> >
> > It is more work to get a builtin and perhaps that could be long term
> > goal, but many items start a simple headers with macros and then migrate
> > into gcc builtins after the general utility is accepted.
>
> Why does it have to be a builtin?
>
> What stops GCC from installing a header?
>
Well I would have to ask. But the facts are that the existing headers
ppc_asm.h and ppu_intrinsics.h seem to be primarily intended for
internal gcc use, are not published in /usr/include, and are not
documented.
We need these to APIs to be easy to find, documented, and durable (a
commitment to be there in the next release).
> Cheers,
> Carlos.
>