Difference between revisions of "EBC Exercise 25 Configuring U-boot"
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− | # Modify u-boot to include your initials in the prompt. (Hint: Look for the omap3_beagle.h file.) | + | # Modify u-boot to include your initials in the prompt. (Hint: Look for the '''omap3_beagle.h''' file for the xM or '''am335x_evm.h''' for the bone.) |
# Learn what is done when the '''boot''' command in entered in u-boot. | # Learn what is done when the '''boot''' command in entered in u-boot. | ||
# Find where the code for boot is defined in the u-boot source. | # Find where the code for boot is defined in the u-boot source. |
Revision as of 05:56, 22 October 2012
Embedded Linux Class by Mark A. Yoder
This follows the approach taken in EBC Exercise 13 Configuring the Kernel. We'll use bitbake to get the source files for U-boot and then we'll edit them.
bitbake
When you did EBC Exercise 22 Cross-Compiling and Finding the Right Kernel u-boot was downloaded and compiled. If you used the default configure, the source code was removed once it was done. Check and see:
host$ cd ~/BeagleBoard/oe/build/tmp-angstrom_v2012_05-eglibc/work/beagleboard-angstrom-linux-gnueabi/ host$ ls
You should see a directory starting with u-boot-
. The rest of the name tells what version you have. Change to that directory and see what's there:
host$ cd u-boot-* host$ ls
If you see a git directory, you are in luck. If you see just a temp directory you need to go back to EBC Exercise 22 Cross-Compiling and Finding the Right Kernel and get it installed.
Once you have the git directory, cd to it and look around.
Compiling U-boot
You can now compile U-boot.
host$ source ~/.oe/crossCompileEnv.sh host$ make host$ scp u-boot.bin root@beagle:.
On the beagle, first be sure the FAT partition is mounted
beagle$ cd /media/ beagle$ mkdir mmcblk0p1 beagle$ mount /dev/mmcblk0p1 mmcblk0p1/ beagle$ cd mmcblk0p1/ beagle$ ls -ls total 354 2 drwxr-xr-x 4 root root 2048 May 16 15:29 Docs 2 drwxr-xr-x 5 root root 2048 May 16 15:29 Drivers 6 -rwxr-xr-x 1 root root 5829 Aug 14 10:10 LICENSE.txt 84 -rwxr-xr-x 1 root root 85058 Aug 14 08:19 MLO 14 -rwxr-xr-x 1 root root 13976 Aug 14 10:10 README.htm 2 -rwxr-xr-x 1 root root 27 Aug 14 10:23 Uenv.txt 2 -rwxr-xr-x 1 root root 178 Aug 14 10:10 autorun.inf 2 -rwxr-xr-x 1 root root 171 Aug 14 10:10 info.txt 238 -rwxr-xr-x 1 root root 241948 Aug 14 08:19 u-boot.img 2 -rwxr-xr-x 1 root root 33 Aug 14 10:23 uEnv.txt.orig
Make a backup of the original u-boot.
beagle$ cp u-boot.bin u-boot.bin.orig beagle$ cp ~/u-boot.bin . beagle$ shutdown -r now
You should now be running the new u-boot.
Assignment
Unfortunately I'm unable to get u-boot to run at this time, so no assignment until further notice.
- Modify u-boot to include your initials in the prompt. (Hint: Look for the omap3_beagle.h file for the xM or am335x_evm.h for the bone.)
- Learn what is done when the boot command in entered in u-boot.
- Find where the code for boot is defined in the u-boot source.
Hint:
u-boot# help boot boot - boot default, i.e., run 'bootcmd' Usage: boot u-boot# print bootcmd bootcmd=if mmc rescan ${mmcdev}; then if userbutton; then setenv bootenv user.txt;fi;echo SD/MMC found on device ${mmcdev};if run loadbootenv; then echo Loaded environment from ${bootenv};run importbootenv;fi;if test -n $uenvcmd; then echo Running uenvcmd ...;run uenvcmd;fi;if run loaduimage; then run mmcboot;fi;fi;run nandboot;
Embedded Linux Class by Mark A. Yoder