Philippe Gerum wrote:
On Thu, 2006-09-14 at 17:47 -0500, Jeff Webb wrote:
I made some more progress in porting my RTLinux application, but now I'm
spinning my wheels trying to track down the source of the following error:
"invalid use of FPU in Xenomai context at ..."
This message also gives the faulty location/symbol+offset. Where does it
point to?
It's coming from some simple floating point operations in my application code.
The relevant code snippet is:
print_msg(TRACE_MSG, "rt_delay_sim\n");
print_msg(INFO_MSG, "jeff rt_delay: 1\n");
actual_dt = sim_dt / rt_speed_factor + rt_skew_correction;
print_msg(INFO_MSG, "jeff rt_delay: 2\n");
The kernel message output is:
Sep 15 09:17:34 kernel: rt_delay_sim
Sep 15 09:17:34 kernel: jeff rt_delay: 1
Sep 15 09:17:34 kernel: invalid use of FPU in Xenomai context at [fc264152]
Sep 15 09:17:34 kernel: Xenomai: suspending kernel thread c1ca3730
('c1ca3730') at
0xfc264152 after exception #7
The variables in question are doubles. The faulty location offset is somewhere
in the rt_delay_sim routine, as you would expect from the output above. This
specific code does not appear to be the problem, though. If I remove the call
to the rt_delay_sim routine, I simply get a floating point exception in another
location.
The strange thing is that I can do a loop of floating point operations at the
beginning of my real-time thread without any problem:
for (i=0; i<1001; i++)
{
f = f * 1.0 + 0.1;
};
print_msg(INFO_MSG, "f = %d\n", (int)f);
but once I get into my real application code, I get the above error after
executing several floating point operations. My 'real application code' is
actually a linked list of routines that reside in other kernel modules. I wish
I could come up with a simple example that caused the same problem... I will
keep trying.
As I said before, I am porting an application that works properly under RTLinux
GPL, and am making some small changes to compile with Xenomai POSIX
threads/timers and RTAI FIFOs.
Thanks,
Jeff
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