Re: TLS question

[Alireza Moshtaghi <alireza dot moshtaghi at ericsson dot com>]

Thanks,
STT_TLS is not set for my extern __thread symbol.
and my linker ends up emitting:

TLS definition in /tmp/cccF5k6P.o section .tbss mismatches non-TLS
reference in /tmp/ccMzRAeS.o

What is responsible for setting this flag? the compiler? or it is set
while the elf is being read? I'm sure I have failed to implement
something in my port.

Thanks
A.

On Thu, 2012-03-22 at 14:53 -0400, Ian Lance Taylor wrote:
> Alireza Moshtaghi <alireza.moshtaghi@ericsson.com> writes:
> 
> > An extern variable is defined as an UND symbol in the elf file, however,
> > when it is classified with __thread, the linker needs to match it up
> > with the correct definition from another object file.
> > The way that I have implemented TLS support in my port of binutils, the
> > linker complains that the extern symbol is not TLS and it can not link
> > it to the definition from the other object file. 
> >
> > The only thing that I can think of is to teach ld to look at the
> > relocation for that symbol and if it is a TLS relocation, it should be
> > able to match the two, but I don't know how to teach ld to do so.
> >
> > Question is: where in the linker I must modify?
> 
> An extern __thread variable should be SHN_UNDEF, STB_GLOBAL, STT_TLS.
> In other words, you don't have to look at relocations, you just have to
> look at the symbol type.
> 
> Ian