[PATCH] PowerPC - Add a faster way to get the thread id

[Steven Munroe]

On Fri, 2012-11-09 at 17:06 -0800, Roland McGrath wrote:
> > So I agree that it should not have be a PPC specific API and it is not a
> > POSIX API, but GLIBC provides other non-POSIX API and I don't understnad
> > why it would be hard to convince the community to add such simple and
> > obviously useful API.
> 
> The core issue is that it is a Linux-centric API that intrinsically depends
> on implementation details that are below the level of the pthreads API.
> It's a pure Linuxism that there is an integer that is unique system-wide
> that corresponds to an individual thread in an individual process.  This is
> the GNU C Library, not the Linux C Library, and we try to be quite
> circumspect about introducing Linuxisms to the GNU system API.
> 

The problem here is that GLIBC has a monopoly on high performance/cached
access to the important data needed for some APIs of the Linux kernel.

I can understand why we should not confuse this with a Posix API. But to
withhold key information that GLIBC holds on the applications behalf and
is specific to Linux I don't understand. Perhaps we need a new class of
__linux_* APIs that will allow access to Linux specific date (auxv, TID,
etc) without impacting Posix.