ERC32 and FPU problems?

Joel Sherrill joel.sherrill at oarcorp.com
Tue Feb 17 11:49:43 UTC 2004


Carl-Johan Hansson wrote:

> I'm using an ERC32 from Atmel(TSC695F) and have problem getting the 
> FPU to work as is should. I'm compiling and linken using 
> "sparc-rtems-gcc -tsc691 -O3 -rtems -g" and if I do a #ifdef 
> CPU_HARDWARE_FP in my main program it looks like it set. But if I use 
> a float instruction I get a trap because I use float without enabling 
> the FPU. The program works if I use -msoft-float, but I know the 
> processor got a FPU and I want to use it!  Anyone got a clue?
>
If you are using the classic API, then you need to spcify that the tasks 
are using floating point.
Otherwise, they will have the FPU disabled and not save the FPU 
context.  This is a safety
and performance thing.  See:

http://www.rtems.com/onlinedocs/releases/rtemsdocs-4.6.0/share/rtems/html/c_user/c_user00054.html
http://www.rtems.com/onlinedocs/releases/rtemsdocs-4.6.0/share/rtems/html/c_user/c_user00065.html

for details.

> _________________________________________________________________
> Hela veckans väder  http://www.msn.se/vader
>
--joel




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