Re: anybody tried NPTL?

[Jun Sun <jsun@mvista.com>]

On Mon, Aug 23, 2004 at 09:28:53AM -0400, Daniel Jacobowitz wrote:
> On Fri, Aug 20, 2004 at 02:46:11PM +0100, Dominic Sweetman wrote:
> > I guess our main message was that we felt it would be a mistake just
> > to add a thread register to o32 (which produces a substantially
> > incompatible new ABI anyway).
> 
> Completely agree...
> 
> > Until that all works, what we had in mind is that we'd do NPTL over
> > o32 by defining a system call to return a per-thread ID which is or
> > can be converted into a per-thread data pointer.  We suspected that
> > NPTL's per-thread-data model allows the use of cunning macros or
> > library functions to make that look OK.
> > 
> > Ought we to go further and see exactly how that can be done?
> 
> It shouldn't be at all hard.  The way NPTL's __thread support works,
> the only things that should have to know where the TLS base is are
> (A) GCC, so it can load it and (B) GDB, via some new ptrace op. 

Are you implying one can implement TLS support without changing O32
ABI?  Interesting...

I know Boris Hu has tried to implemented NPTL with another approach which
does not rely on TLS support (use "--without-tls").  According to him
this approach is getting harder these days.

Jun