Philippe Gerum wrote:
On Tue, 2006-09-26 at 18:28 +0200, Wolfgang Grandegger wrote:
Philippe Gerum wrote:
On Tue, 2006-09-26 at 16:56 +0200, gilles.chanteperdrix wrote:
---------- Debut du message initial -----------

Copies :
Date   : Tue, 26 Sep 2006 16:21:18 +0200
Objet  : Re: [Xenomai-core] Problem with periodic timer on
PPC40x solved

On Mon, 2006-09-25 at 22:29 +0200, Niklaus Giger wrote:
Am Montag, 25. September 2006 17:57 schrieb Philippe
On Sun, 2006-09-24 at 23:07 +0200, Wolfgang
Grandegger wrote:
Niklaus Giger wrote:
Is the output of lines like "Xenomai: Switching
display-3238 to secondary
mode after exception #1025 from user-space at
0x100033c4 (pid 3240)"
harmless or the result of a activated
A known hw issue seems to exist with the 405GP (revD), which
causes the
ESR to be incorrectly set upon FPU emulation trap, which
would in turn
cause the spurious exception to be relayed to the nucleus by
Adeos. The
patch below is _not_ the final fix, but rather a way to
check if this
message is indeed related to the FPU emulation on your
board. Does it
silence the exception without breaking the box?
The FPU fault may be the result of the latency display thread
using the
FPU: on systems with emulated FPU, this looks normal.

This said, we should not switch the task to secondary mode, but rather
emulate the FPU ops in primary mode. To this end, we need to make sure
that do_mathemu() is not going to choke over this context (e.g.
preemption count check issues over CONFIG_PREEMPT when running
unmodified uaccess routines). We additionally need to fix the program
check exception handler to give the math emulation code a chance to
handle the fault before we complain loudly at the nucleus.
OK, but in general, soft-float emulation should be used on systems without FPU and this is even more important for real-time.

Makes sense. So maybe we should make this a more explicit and formal
warning, to catch missing soft float emulation, actually.

We could already print a compiler warning when the kernel is built with MATH_EMULATION=y. There are a few corner-case where it might make sense to have math emulation enabled e.g. you need to run a binary with hard FP instructions because you are unable to rebuild it from the sources.

This is a tool chain issue. Niklaus, what tool chain are you using?


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