MIPS Thread Local Storage Help Request

[Joel Sherrill]

Hi

This is going to be interesting. MIPS TLS is broken because
we don't have a trap handler for this. From GCC:

;; Thread-Local Storage

;; The TLS base pointer is accessed via "rdhwr $3, $29".  No current
;; MIPS architecture defines this register, and no current
;; implementation provides it; instead, any OS which supports TLS is
;; expected to trap and emulate this instruction.  rdhwr is part of the
;; MIPS 32r2 specification, but we use it on any architecture because
;; we expect it to be emulated.  Use .set to force the assembler to
;; accept it.
;;
;; We do not use a constraint to force the destination to be $3
;; because $3 can appear explicitly as a function return value.
;; If we leave the use of $3 implicit in the constraints until
;; reload, we may end up making a $3 return value live across
;; the instruction, leading to a spill failure when reloading it.

This code from NetBSD appears to be the core part of the
handler.

http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/arch/mips/mips/locore_mips3.S?only_with_tag=MAIN

If someone can adapt this, then the MIPS will have working
TLS.

Thanks.

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at OARcorp.com        On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
Support Available                (256) 722-9985