Re: thread-ready ABIs

["H . J . Lu" <hjl@lucon.org>]

On Mon, Jan 21, 2002 at 10:36:26AM -0800, Ulrich Drepper wrote:
> "H . J . Lu" <hjl@lucon.org> writes:
> 
> > Ulrich, should applciations have access to thread register directly?
> 
> It doesn't matter.  The value isn't changed in the lifetime of a
> thread.  So the overhead of a syscall wouldn't be too much.  And
> protection against programs overwriting the register isn't necessary.
> It's the program's fault if that happens.

Thq question is if we should reserve $23 outside of glibc. $23 is
a saved register in the MIPS ABI. It doesn't change across function
calls. If applications outside of glibc don't need to access the
thread register directly, that means $23 can be used as a saved
register. We don't have to change anything when compiling applications.
We only need to compile glibc with $23 reserved as the thread register.


H.J.