SPARC fp_disabled exception

Ingolf Steinbach ingolf.steinbach at
Sat Aug 9 19:19:06 UTC 2008

2008/8/7 Jerry Needell <jerry.needell at>:
> Is there a concern that if the
> compiler allows an ISR to utilize FPU registers, then the FPU
> registers will not be properly restored after the ISR?

I'd assmume the FPU context to be properly restored after the ISR.
However, the FPU might not be enabled, so FPU instructions will
trigger an FPU disabled trap. In case an RTEMS_FLOATING_POINT task is
interrupted by the ISR, you might be lucky and the FPU is still
enabled within the FPU. However, when a non-FPU task is interrupted,
the FPU will most certainly be disabled when executing the ISR.

Note: This is my assumtion on how things are currently implemented.
Someone with more knowledge than me should confirm / correct these


More information about the users mailing list