Pb with FPUsupport and VMalloc activated on PPC platform

Wolfgang Grandegger wolfgang.grandegger at bluewin.ch
Wed Oct 27 13:28:10 CEST 2004

On 10/27/2004 12:33 PM Nicolas Genevrier wrote:
> Hello,
> we have a configuration who needs FPU support, and due to amount of dynamic
> memory, we use VMalloc in the RTAI allocator.

You mean the RTAI memory allocater? I never got that working and for
this reason it's disabled by default.

> We use RTAI 3.0r2 (same problem with 3.0r4) on kernel 2.4.25, on a Men B11
> board (processor = MPC8245).

What kind of problems do you have with 3.0r4?

> The problem is that in RT tasks, we get bus errors when calling rt_sleep.
> After more investigation, it is due to the save and restore of processor
> flags in rt_sleep code.
> We have the same problem with a RT task who just make loops on the following
> code :
> unsigned long flags;
> flags = rt_global_save_flags_and_cli();    // Save flags
> rt_global_restore_flags(flags);                // Restore them

Hm, this is an interesting hint.

> This problem does'nt appear on X86 architecture.

Yes, vmalloc support is working on X86.

> Can anyone give us a hint about such problems ?
> Has anyone already used both FPU support and VMalloc on rtai 3 on PPC ?

FPU support is working but there are known problems with vmalloc.


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