GCC SPARC FPU issue status

Manuel Coutinho manuel.coutinho at edisoft.pt
Tue Sep 1 08:50:53 UTC 2009



Was checking some mails exchanged in this mailing list a while ago (2006)
(http://www.rtems.com/ml/rtems-users/2006/may/msg00040.html) and would like
to know if the issue concerning GCC and SPARC floating point registers is
now solved or not. Does anybody know the status of this issue? Is there a
bug in GCC bugzilla so that we can track this? try to find but with no luck


Briefly, the problem, as far as I understood, occurs when a function
receives multiple arguments: GCC might store some arguments on FPU
registers, which could cause all sort of problems, like an invalid FPU trap,
or an erroneous result on a thread that uses FPU (because the register was

This problem could be solved by compiling RTEMS with -msoft-float flag and
the application without this flag (for the sections that want to use
floating point).


It also seams that ERC32 has a different behavior than Leon2 and Leon3: for
Leon2 and Leon3, RTEMS does not save/restore hardware FPU during a context
switch. Is this correct? Shouldn't the 3 BSPs have the same behavior?
Shouldn't leon2 and leon3 save/restore the FPU hardware during a context


(I'm looking at RTEMS 4.8.0)


Thanks in advance

Kind regards

Manuel Coutinho


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