libgcj and the NPTL posix threads implementation

Mon Mar 1 22:52:00 GMT 2004

On Mon, 1 Mar 2004, Boehm, Hans wrote:
> I assume both of the proposals below retrieve a value stored at an offset from
> %gs? (What's "move"? Is it different from "mov" or a typo?)

Sorry. s/move/movl/
> Won't %gs itself do as
> a thread-specific value? Doesn't that always point to a thread-specific
> area, independent of the thread package and tls implementation?

I don't know. Like Anthony, I see the same %gs value in each thread,
whether accessing the register directly or viewing in gdb. So I'm
guessing the kernel instead swaps page tables, instead of segment
registers, when switching context between threads.
The TLS x86 ABI is documented (section 3.4.2) in:
http://people.redhat.com/drepper/tls.pdf
Jeff