Some notes on getting a Xenomai system running under buildroot.

Build environment

- Installed Ubuntu 12.04 LTS.

- Downloaded buildroot-2011.11.

- Added build-essential, automake, bison, gawk, perl, zlib devel, ncurses devel, perhaps some other packages NB: If you are missing buildroot dependencies and you find out half-way through a build, rebuild from scratch, or risk getting a non-working system.

Buildroot/Xenomai version selection

The easiest way to do this without having to mess around with grub is to create a bootable CD image. Versions of buildroot up to 2012.08 support this. Choosing Kernel headers 3.4.X and kernel version 3.4.6 allows the ipipe-core-3.4.6-x86-2.patch from Xenomai 2.6.2 to be applied.

So we:

- Use 2012.08 Buildroot

- Bump Xenomai version to 2.6.2 (the latest)

- Remove lfs patch from Buildroot/package/xenomai directory as it won't apply to Xenomai 2.6.2.

Buildroot configuration.

# make menuconfig

Target Architecture -> i386

Target Architecture Variant -> i486

Toolchain -> Kernel Headers -> 3.4.x #### NB: This means we'll download two kernels, not one!

System Configuration -> Port to run a getty -> tty1

Package selection -> Real-Time -> Xenomai Userspace

Filesystem Images -> iso image

Bootloaders -> syslinux -> Install isolinux

Kernel -> Kernel version -> Same as toolchain kernel

Kernel -> Kernel configuration -> Using a defconfig

Kernel -> Defconfig name -> i386

Kernel -> Linux Kernel extensions -> Adeos/Xenomai real-time patch [*]

*** Now run 'make' to build the toolchain/download the kernel ***

Configure the kernel

# make linux-menuconfig

Filesystems -> Second extended fs support (ANNOYING BUG IN BUILDROOT!!)

Power management and ACPI options -> Power management support -> [ ]

Power management and ACPI options -> CPU Frequency scaling -> [ ]

Real-time sub-system -> machine -> enable fpu support -> [ ]

# make

Due to a bug in VirtualBox, it won't boot the ISO rootfs because it is called rootfs.iso9660. Rename it to rootfs.iso, or make a link, and then VirtualBox will boot OK.

Compiling simple Xenomai example using Xenomai native interface

Get an example

Since we've not really 'installed' Xenomai on this machine, we have to fiddle about. First figure out what flags we need:

# cd ./output/host/usr/i486-unknown-linux-uclibc/sysroot

# ./usr/bin/xeno-config --skin native --cflags

-I/usr/include/xenomai -D_GNU_SOURCE -D_REENTRANT -Wall -pipe -D__XENO__

# ./usr/bin/xeno-config --skin native --ldflags

-lnative -L/usr/lib -lxenomai -lpthread

Use what we found to create a simple makefile, with includes and libs relative to the sysroot location. Put it in a directory beside the buildroot one.







CFLAGS:=-I$(SYSROOT)/usr/include/xenomai -D_GNU_SOURCE -D_REENTRANT -Wall -pipe -D__XENO__

LDFLAGS:=-lnative -L$(SYSROOT)/usr/lib -lxenomai -lpthread

all: trivial-periodic

trivial-periodic.c : $(BUILD)/xenomai-2.6.2/examples/native/trivial-periodic.c

cp $< $@

trivial-periodic.o : trivial-periodic.c

$(CC) $(CFLAGS) -o $@ -c $<

trivial-periodic : trivial-periodic.o

$(CC) -o $@ $< $(LDFLAGS)

The file 'trivial-periodic' can be copied into the VM and run. For some reason ldd reports different required libraries to the ones that exist on the target, but it doesn't seem to matter. The binary runs fine. It segfaults after aborting with ctrl-C though.