Re: __thread support in -current..

see my answer to you there..


On Tue, 17 Jun 2003, Marcel Moolenaar wrote:

> On Tue, Jun 17, 2003 at 03:34:15PM -0700, Julian Elischer wrote:
> > 
> > Ok, so having thrashed out what is required on the threads list 
> > (and severely strained (but hopefully not permanently) our relations 
> > with the OpenGL folks) we've figured out that we do need to support
> > __thread (if we don't we'll miss out on  alot).
> > 
> > I have basicaly worked out what we need to do 
> > (Generarlly we do the same as solaris does) to support this..
> > The question is, what do we need to do for gcc and the loader
> > to support this..?
> > 
> > I guess the support is in gcc as Linux and solaris use it, but
> > is our linker close enough to what they use to be able to benefit at all
> > from them?
> 
> >From my posting to threads_at_:
> 
> \begin{quote}
> ... To support the __thread
> keyword, our thread library needs to create the TLS as defined in the
> binary and its dependent shared libraries by virtue of the .tdata and
> .tbss sections/segments, based on the image of the TLS as constructed
> by the RTLD for the initial set of modules (created for the initial
> thread) and amended by TLS space defined in the dynamicly loaded
> libraries; and the TLS has to be created for every new thread at the
> time the thread itself is created. This TLS allocation has to be made
> accessable in accordance with runtime specifications for the supported
> architectures (libthr: i386 & ia64; libkse: i386 currently -- more to
> follow) and in line with the access sequences created by the compiler,
> and using the static relocations known to the static linker and dynamic
> relocations of which the support needs to be added to RTLD.
> 
> The static TLS model requires the least amount of work: add support
> to allocate the TLS image for every thread creation and point the
> thread pointer to it in a way compatible with the runtime spec.
> 
> The dynamic TLS model requires more substantial changes and involves
> RTLD as well. This is the model that requires __tls_get_addr().
> \end{quote}
> 
> HTH,
> 
> -- 
>  Marcel Moolenaar	  USPA: A-39004		 marcel_at_xcllnt.net
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