sparc and trap 4 (floating point disabled)

[Joel Sherrill]

On Tue, Dec 3, 2019 at 8:48 AM Schweikhardt, Jens (TSPCE3-TL4) <
Jens.Schweikhardt at tesat.de> wrote:

> Hello, world\n
>
>
>
> I have a question about the use of trap 4 by RTEMS on Sparc32 (leon3).
>
> Since our app needs FP, we set the PSR[EF] bit during the boot process
> before RTEMS is invoked.
>
> Since we don’t expect the fp_disabled trap (4) to occur, we install a
> fatal handler for it with
>
> rtems_interrupt_catch(&fatalTrapHandler, 4, &old);
>
>
>
> However, the fatalTrapHandler is invoked a short time after application
> start (we use the Init() task
>
> and start a handful of additional tasks, all of which have attribute
> RTEMS_FLOATING_POINT)
>
> and the PSR[EF] bit is indeed cleared. None of our tasks
>
> clears that bit, so we suspect RTEMS does it for some reason.
>

Is the Init task floating point? What thread is executing when the trap
occurs?

The IDLE thread is likely integer only if you are looking at it is running.


>
>
> Question: is an RTEMS/sparc application allowed to install a handler for
> trap 4? I could not find an
>
> answer in the docs for SPARC Specific Information.
>

I think that's OK.

>
>
> Thanks for any insight!
> Regards, Jens
>
>
>
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