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RE: libgcj and the NPTL posix threads implementation
- From: Jeff Sturm <jsturm at one-point dot com>
- To: "Boehm, Hans" <hans dot boehm at hp dot com>
- Cc: "'Anthony Green'" <green at redhat dot com>, "'Michael Koch'" <konqueror at gmx dot de>, <java at gcc dot gnu dot org>
- Date: Mon, 1 Mar 2004 17:52:47 -0500 (EST)
- Subject: RE: libgcj and the NPTL posix threads implementation
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