Date: Mon, 29 Mar 2004 14:36:32 -0500 (EST) From: Daniel Eischen <eischen@vigrid.com> To: Doug Rabson <dfr@nlsystems.com> Cc: freebsd-threads@freebsd.org Subject: Re: Thread Local Storage Message-ID: <Pine.GSO.4.10.10403291433500.17631-100000@pcnet5.pcnet.com> In-Reply-To: <200403292000.13794.dfr@nlsystems.com>
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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. -- Dan Eischen
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