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TLS run-time requirements on x86, etc.
- From: Joel Sherrill <joel dot sherrill at oarcorp dot com>
- To: GCC Mailing List <gcc at gcc dot gnu dot org>
- Date: Thu, 12 Jan 2017 11:22:58 -0600
- Subject: TLS run-time requirements on x86, etc.
- Authentication-results: sourceware.org; auth=none
Hi
I am looking at the RTEMS x86 TLS support. When -fPIC is
specified, gcc generates calls to ___tls_get_addr(). But
when it is not specified, there are no external calls.
To make sure we are doing the right thing, I have a
few questions:
+ What is expected for "get TLS" when __tls_get_addr()
is not called?
+ Can we force all RTEMS i386 gcc configurations to make the
function call to __tls_get_addr()? We have an implementation
of it for ARM so it would be the same. So this would
be a simple solution for us.
+ Is there any reference material to show what is expected
for each architecture? I think the MIPS generates an illegal
instruction and you end up doing TLS in there. It would be
easier if we could configure gcc to make subroutine calls
to __tls_get_addr() instead generically?
Anything else about TLS and run-time requirements we
should know?
--
Joel Sherrill, Ph.D. Director of Research & Development
joel.sherrill@OARcorp.com On-Line Applications Research
Ask me about RTEMS: a free RTOS Huntsville AL 35806
Support Available (256) 722-9985