[linuxkernelnewbies] Angstrom - Crashcourse Wiki

Tue, 20 Oct 2009 09:05:37 -0700

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Angstrom

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BeagleBoard Angstrom links

Interesting places to start reading ...

Installing and booting the pre-built images

If you just want to download, flash and boot, get the latest kernel uImage file (the 2.6.29 version will work) and root filesystem tarball from the [Angstrom BeagleBoard download page] and do the normal SD card things with them. Use the U-Boot bootargs "console=ttyS2,115200n8 console=tty0 root=/dev/mmcblk0p2 rw rootfstype=ext3 rootwait".

If you have a TI DLP pico projector, apparently, the pre-built Angstrom kernel image is configured to work with that by default, so you don't need to mess around with any "omapfb" video boot settings.

Be patient the first time you boot -- there's a good deal of firstboot configuration to be done. And your login username is "root", with no password.

Building Angstrom from scratch with OpenEmbedded

A recipe that appears to work on Fedora 11 -- your mileage may vary. (The same recipe appears to work on the beta release of Fedora 12 x86_64, at least to the extent that I've tested it.)

/proc/sys/vm/mmap_min_addr

Before you get rolling, you might as well ensure that this kernel variable is set to zero; otherwise, OE will complain later. You can temporarily set it manually for now: 

# echo 0 > /proc/sys/vm/mmap_min_addr

or add the following line to /etc/sysctl.conf: 

vm.mmap_min_addr = 0

and run sysctl -p to reconsult the file. Whatever works for you.

(If you're trying this with Fedora 12 Beta, then running that last command will generate a few errors related to iptables and bridging. They can be safely ignored.)

NOTE: This setting on Fedora 12 Beta (and perhaps on Fedora 11 and other distros) causes an SELinux error later. In order to avoid that error, you can de-activate SELinux, or run the command: 

# setsebool -P allow_unconfirmed_mmap_low 1

Installing bitbake

As long as you check out and build from only the stable branch, bitbake is already available as it's bundled with the stable branch so you don't need to mess with anything here. If, however, you want to work with the development branch, you'll have to install bitbake yourself separately. If you do that, install manually from the 1.8.12 version of the tarball. Fedora does, in fact, have a bitbake package in its repo, but it's only version 1.8.10. I've already put in a request to have that updated to 1.8.12.

Installing help2man and texi2html

If you don't have these, OE will complain. On Fedora, just: 

# yum install help2man texi2html

On other distros, whatever.

Installing glibc-static (Fedora 11)

Fedora 11 is the first version of Fedora that has broken out the static linking portion of glibc into a separate package so if you're running Fedora 11 (or 12 Beta), you'll need to: 

# yum install glibc-static

otherwise your build of module-init-tools-cross will fail.

Getting the OE metadata

(Based heavily on [this page].)

Decide first where you want all of this to happen -- say ~/oe -- and set the environment variable OETREE to that directory location. Once that's done: 

$ mkdir -p ${OETREE}
$ cd ${OETREE}
$ git clone git://git.openembedded.org/openembedded.git openembedded
$ cd openembedded
$ git checkout origin/stable/2009 -b stable/2009

And every so often, if you want to stay up-to-date: 

$ cd openembedded
$ git pull

You are, of course, free to build from the development branch as well.

Configuring OE for Angstrom on Beagleboard 

$ cd ${OETREE}
$ mkdir -p build/conf
$ cp openembedded/contrib/angstrom/local.conf build/conf

after which you should edit build/conf/local.conf, make the appropriate changes, and add the line: 

MACHINE = "beagleboard"

Finally, grab the file [source-me.txt] and copy it into the ${OETREE} directory for later. That file will contain an assignment for the environment variable OETREE. You can either adjust that to where you created your OE directory, or remove it entirely if you set that permanently in your personal .bash_profile.

NOTE: Sourcing that file relocates you into the build subdirectory, so you need to cd up again before doing the build.

Doing the build

Set up your build environment with: 

$ cd ${OETREE}
$ source source-me.txt
$ cd ..

then go to work building an image: 

$ cd openembedded
$ bitbake base-image

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