Re: [HACKERS] Threads vs Processes

[Kurt at DBC <kurtw(at)dbc(dot)co(dot)nz>]

Tom Lane wrote:
> I assume you mean static as in not-auto, rather than static as in
> not-global.  Otherwise we have a problem here.
[...]
> Surely the addresses can be assumed constant within a thread.  Otherwise
> we have a problem here too.
[...]
> > Taking addresses of TLS variables should be considered illegal,
> Sorry, no can accept that restriction.

I think you are okay on all 3 fronts,
from http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local :

"The __thread specifier may be used alone, with the extern or static 
specifiers, but with no other storage class specifier. When used with 
extern or static, __thread must appear immediately after the other 
storage class specifier."

and

"When the address-of operator is applied to a thread-local variable, it 
is evaluated at run-time and returns the address of the current thread's 
instance of that variable. An address so obtained may be used by any 
thread. When a thread terminates, any pointers to thread-local variables 
in that thread become invalid."

Also see "ISO/IEC 9899:1999 Edits for Thread-Local Storage" :
http://gcc.gnu.org/onlinedocs/gcc/C99-Thread-Local-Edits.html#C99%20Thread-Local%20Edits

and ELF Handling For Thread-Local Storage,
http://people.redhat.com/drepper/tls.pdf may be of interest.

Cheers,
Kurt.