Date: Mon, 29 Mar 2004 22:21:00 +0100 From: Doug Rabson <dfr@nlsystems.com> To: Daniel Eischen <eischen@vigrid.com> Cc: freebsd-threads@freebsd.org Subject: Re: Thread Local Storage Message-ID: <200403292221.00286.dfr@nlsystems.com> In-Reply-To: <Pine.GSO.4.10.10403291433500.17631-100000@pcnet5.pcnet.com>
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On Monday 29 March 2004 20:36, Daniel Eischen wrote: > On Mon, 29 Mar 2004, Doug Rabson wrote: > > I've been spending a bit of time recently familiarising myself with > > this TLS stuff and trying out a few things. I've been playing with > > rtld and I have a prototype patch which implements enough TLS > > support to let a non-threaded program which uses static TLS work. > > With a tiny bit more work I can have limited support for dynamic > > TLS as well (not for dlopen'ed modules yet though). Is there a p4 > > tree for this stuff yet? I'd like to check in what I have sometime. > > > > I've also been looking at libpthread and I can see some potential > > problems with it. Currently libpthread on i386 uses %gs to point at > > a struct kcb which seems to be a per-kse structure. This structure > > contains a pointer to a per-thread struct tcb and this pointer is > > managed by the userland context switch code. Other arches are > > similar, e.g. ia64 uses $tp to point at struct kcb. > > > > The problem with TLS is that the i386 ABI needs %gs to point at the > > TLS > > There are 2 different methods allowed for the i386 ABI. > We want to use the other method in which there is an > additional indirection. The current i386 libpthread > stuff adheres to this method. Surely the GNU TLS ABI is preferable? It generates much smaller code and needs many fewer relocations.home | help
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