Jeff Webb wrote:
If I run the attached program, I get the following result:
[root]# ./mqtest2
CPU time limit exceeded
The kernel log contains:
Oct 25 14:13:03 kernel: invalid use of FPU in Xenomai context at
0x80492f6
I have another piece of information on this problem. I was able to test the program on two other machines:
an Athlon XP, and a PIII laptop. The program works on the PIII, but fails on the Athlon XP. I then compiled
a new kernel, selecting the "Pentium-Pro" processor family instead of the
"Athlon/Duron/K7" processor family. The mqtest2 program now works on my Athlon64 X2 and Athlon XP
systems, if I use the "Pentium-Pro" kernel.
Here is a summary of what I tried:
Machine #1: AMD Athlon(tm)64 X2 Dual Core Processor 4400+
OS: Fedora Core 5
a) Linux SMP 2.6.17.13 (K7 config) / Xenomai 2.2.4 -> mqtest2 fails
b) Linux SMP 2.6.17.13 (K7 config) / Xenomai trunk r1749 + patch -> mqtest2
fails
patch = https://mail.gna.org/public/xenomai-core/2006-10/msg00069.html
c) Linux UP 2.6.17.13 (K7 config) / Xenomai 2.2.4 -> mqtest2 fails
d) Linux SMP 2.6.17.13 (K7 config) / Xenomai 2.2.1 -> mqtest2 fails
e) Linux UP 2.6.17.13 (ppro config) / Xenomai 2.2.4 -> mqtest2 WORKS!
Machine #2: AMD Athlon(tm) XP 3200+
a) Fedora Core 1 / Linux 2.4.32 (K7 config) / Xenomai 2.2.3 -> mqtest2 fails
b) Fedora Core 5 / Linux 2.6.17.13 (ppro config) / Xenomai 2.2.4 -> mqtest2
WORKS!
Machine #3: Intel Pentium III Mobile CPU
OS: Debian Unstable (old)
Linux 2.4.33.3 (ppro config) / Xenomai 2.2.4 -> mqtest2 WORKS!
So, it seems that a bug is introduced when compiling for the AMD K7 family. Is
the mqtest2 problem a compiler optimization bug, a Linux bug, a Linux
configuration problem, a Xenomai bug, or a problem in my code? Any ideas on
how to proceed? I am not familiar with the Xenomai internals or low-level x86
code, but I will do what I can to help debug this.
Does anyone else have an AMD system that can verify my results?
The mqtest2.c program in question was attached here:
https://mail.gna.org/public/xenomai-help/2006-10/msg00147.html
The problem seems to be connected with the size of writes to Xenomai pipes.
This example uses POSIX message queues, but I had a similar problem a while
back with RTAI pipes. Maybe this tells us the problem is in the nucleus pipe
code? Just a guess. The problem seems to affect both 2.4 and 2.6 systems, and
goes back to at least Xenomai 2.2.1.
Thanks,
Jeff
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