EBC Xenomai

From eLinux.org
Revision as of 12:54, 24 October 2014 by Yoder (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

thumb‎ Embedded Linux Class by Mark A. Yoder


Xenomai is a set of patches for the kernel that allow it to run real-time tasks. This is an adaptation of Bruno Martins' Xenomai on the Beaglebone Black in 14 easy steps that works with the kernel installed in EBC Installing Kernel Source.

Patching the Kernel

host$ wget http://download.gna.org/xenomai/stable/latest/xenomai-2.6.4.tar.bz2
  • Checkout the latest kernel
host$ cd bb-kernel/KERNEL
host$ uname -a
host$ git tags | sort | less

Pick the tag that is close to your current version of the kernel.

host$ git checkout 3.8.13-bone67 -b xenomai
  • Patch the kernel. This assumes bb-kernel and xenomai-2.6.4 are at the same directory level.
host$ cd bb-kernel/KERNEL
host$ patch -p1 < ../../xenomai-2.6.4/ksrc/arch/arm/patches/beaglebone/ipipe-core-3.8.13-beaglebone-pre.patch
host$ patch -p1 < ../../xenomai-2.6.4/ksrc/arch/arm/patches/ipipe-core-3.8.13-arm-4.patch
host$ patch -p1 < ../../xenomai-2.6.4/ksrc/arch/arm/patches/beaglebone/ipipe-core-3.8.13-beaglebone-post.patch
  • Then one more patch from [1], which is shown here.
host$ cat > thumb.patch
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index e2bc263..6f4d9f0 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -469,6 +469,7 @@ __irq_usr:
 	kuser_cmpxchg_check
 	irq_handler
 #ifdef CONFIG_IPIPE
+THUMB(	it	ne )
 	bne	__ipipe_ret_to_user_irqs_disabled
 #endif	/* CONFIG_IPIPE */
 	get_thread_info tsk
@@ -767,6 +768,7 @@ ENTRY(ret_from_exception)
 	disable_irq
 	bl	__ipipe_check_root
 	cmp     r0, #1
+THUMB(	it	ne )
 	bne	__ipipe_ret_to_user_irqs_disabled  @ Fast exit path over non-root domains
 #endif /* CONFIG_IPIPE */
 	get_thread_info tsk
host$ patch -p1 < thumb.patch
  • Prepare the kernel
host$ cd ../../xenomai-2.6.4/scripts
host$ ./prepare-kernel.sh --arch=arm --linux=../../bb-kernel/KERNEL/

Compile the Kernel

host$ cd ../../bb-kernel

Make sure AUTO_BUILD is turned off.

host$ vi system.sh

Be sure the last line commented out.

#AUTO_BUILD=1
  • Build the kernel
host$ tools/rebuild.sh
  • When the configuration menu comes up
    • Under CPU Power Management ---> CPU Frequency scaling, disable [ ] CPU Frequency scaling.
    • Under Real-time sub-system ---> Drivers ---> Testing drivers, enable everything

Then sit back and wait a while.

Setting up the Bone

While you are waiting for the compile to finish, you can set up the Bone.

  • Copy Xenomai to the Bone. I'm assuming the Bone is at 192.168.7.2.
host$ scp -r xenomai-2.6.4 192.168.7.2:.
  • On the Bone
bone$ cd xenomai-2.6.4
bone$ ./configure CFLAGS="-march=armv7-a -mfpu=vfp3" LDFLAGS="-march=armv7-a -mfpu=vfp3"
bone$ make
bone$ make install

The configure takes about a minute, the make six more minutes and the install another minute.

Copy the drivers.

bone$ cd; mkdir xenomai_drivers; cd xenomai_drivers

host$ cd bb-kernel/KERNEL/drivers/xenomai/testing
host$ scp *.ko 192.167.7.2:xenomai_drivers

bone$ insmod xeno_klat.ko

Running Tests

Now, run some tests.

User-mode latency.

bone$ /usr/xenomai/bin/latency
== Sampling period: 1000 us
== Test mode: periodic user-mode task
== All results in microseconds
warming up...
RTT|  00:00:01  (periodic user-mode task, 1000 us period, priority 99)
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst
RTD|      3.624|      3.833|     20.458|       0|     0|      3.624|     20.458
RTD|      2.749|      3.749|     22.583|       0|     0|      2.749|     22.583
RTD|      2.749|      4.583|     25.499|       0|     0|      2.749|     25.499
RTD|      2.749|      3.708|     20.541|       0|     0|      2.749|     25.499
RTD|      2.749|      3.749|     21.916|       0|     0|      2.749|     25.499
^C---|-----------|-----------|-----------|--------|------|-------------------------
RTS|      2.749|      3.916|     25.499|       0|     0|    00:00:05/00:00:05

In-kernel latency

bone$ /usr/xenomai/bin/klatency
== Sampling period: 100 us
== Test mode: in-kernel periodic task
== All results in microseconds
warming up...
RTT|  00:00:00  (in-kernel periodic task, 100 us period, priority 99)
RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
RTD|      -3.055|      -2.295|       1.903|       0|      -5.885|      11.207
RTD|      -2.430|      -2.298|       1.653|       0|      -5.885|      11.207
RTD|      -2.389|      -2.307|       1.611|       0|      -5.885|      11.207
RTD|      -2.389|      -2.300|       2.236|       0|      -5.885|      11.207
RTD|      -4.306|      -2.192|       3.486|       0|      -5.885|      11.207
RTD|      -2.890|      -2.298|       2.360|       0|      -5.885|      11.207
RTD|      -3.265|      -2.294|       2.694|       0|      -5.885|      11.207
RTD|      -3.057|      -2.295|       2.777|       0|      -5.885|      11.207
RTD|      -3.098|      -2.297|       2.276|       0|      -5.885|      11.207
RTD|      -4.849|      -2.188|       4.276|       0|      -5.885|      11.207
RTD|      -3.153|      -2.272|       2.847|       0|      -5.885|      11.207
RTD|      -2.445|      -2.313|       1.805|       0|      -5.885|      11.207
RTD|      -3.195|      -2.195|       3.721|       0|      -5.885|      11.207
^CRTD|      -2.404|      -2.312|       2.180|       0|      -5.885|      11.207
---|------------|------------|------------|--------|-------------------------
RTS|      -5.885|      -2.275|      11.207|       0|    00:00:03/00:00:03

Poke around some

bone$ ls /proc/xenomai
acct      faults       irq      registry/  schedclasses/  timer
affinity  heap         latency  rtdm/      stat           timerstat/
apc       interfaces/  lock     sched      timebases      version
bone$ ls -F /proc/ipipe
Linux  version  Xenoma
bone$ cat /proc/xenomai/version
2.6.4
bone$ cat /proc/ipipe/version
4




thumb‎ Embedded Linux Class by Mark A. Yoder