Modifying and rebuilding u-boot

Customizing u-boot to change pin mux settings on the BeagleBoard.

I highly recommend starting with a fresh OE/Angstrom install following these directions.

NOTE: This process is not as easy as it should be because the default ‘local.conf’ includes the line:

 INHERIT += " rm_work "

which removes the source after everything has been compiled and deployed–this leads to a lot of confusion when reading posts that say the source can be found in ‘tmp/work…’ or ‘angstrom-dev/work…’.  Having previously built images will also populate your folders with a lot of stuff that is extraneous, and that’s why I recommend a fresh install.

Also, I did port over my local overlay as described here, adding ‘${OETREE}/local/recipes/*/*.bb’ to the BBFILES assigment in the ‘local.conf’ file.  I did this to include my app, not to update u-boot.  I did this before invoking any bitbake commands in the links mentioned above.

I then performed a bitbake of my own image, from my local overlay (which builds on console-image) with:

$ bitbake cmma-ptrp-image

(This could have just as easily been:

$ bitbake console-image

for a default install without a local overlay.)

This ran for a few hours and completed successfully.  Since I was then unable to find the u-boot source code  under ‘${OTREE}/angstrom-dev/work…’ (I suspect due to the default use of the rm_work task) I ran the following:

$ source ${OETREE}/source-me.txt
$ bitbake -f -c clean -b ../recipes/u-boot/
$ bitbake -f -c compile -b ../recipes/u-boot/

which forces a recompile of u-boot, leaving the source in place.  I then found the source in:


After applying my pin mux modifications in board/omap3/beagle/beagle.c (see the bottom of this post) I ran the following:

$ bitbake -f -c compile -b ../recipes/u-boot/
$ bitbake -f -c deploy -b ../recipes/u-boot/

I was then able to copy ‘u-boot-beagleboard.bin’ in ‘${OETREE}/angstrom-dev/deploy/glibc/images/beagleboard’ to my SD card.

After rebooting the beagleboard and logging in, the command:

$ cat /etc/services > /dev/ttyS0

results in a wiggly line on the scope connected to pin 15 of J5 on the beagleboard, the UART1_TX line.

2 replies on “Modifying and rebuilding u-boot”

Thanks for the clear answer and useful suggestion.
I’m not pretty sure calling twice compile does any good.
I tested on my rev c2 Beagleboard, I only add mux definitions in #define MUX_BEAGLE_C() \ that is called at the very end of beagle.c and I see that even introducing modifications in beagle.h , bitbake complains there is nothing to do.

So I tested

bitbake -c clean
bitbake -c configure u-boot_git.bin

modify the beagle.h

bitbake -c compile u-boot_git.bin
bitbake -c deploy u-boot_git.bin

now in your
you should have a working u-boot. Now UART1, I2C2 (with external pullup), I2C3 (without pullup) and GPIO work.

I’m trying hard on the other hand to have my spi4 working and LCD too..,

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