Compile a uBoot Kernel

This is a tutorial of how to compile a 2.6.21+ kernel from vanilla gentoo-sources or from kernel.org sources to suit UBoot bootloader

While this article was originally written for Gentoo users, it is basically the same for Debian or others distros. Note that this article is valid for the KuroBox, LS1, LS-HG, KuroHG and the LS-HS.

Gentoo
emerge -av dtc

Note: you may already have a version at /boot/dtc. However emerging explicitly puts dtc in the path and gives you the latest version.

Debian
apt-get install build-essential uboot-mkimage module-init-tools device-tree-compiler

Gentoo
Get the latest stable kernel sources
 * 1) emerge -ua gentoo-sources

make a link to the kernel sources
 * 1) cd /usr/src
 * 2) ln -sfn linux-2.6.* linux

Debian and other
cd /usr/src wget http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.*.tar.bz2 *(check for latest version) tar xjvf linux-* ln -sfn linux-* linux

Edit your kernel config
Clean up before you begin:
 * 1) cd /usr/src/linux
 * 2) make mrproper

Use the default KuroBox config:
 * 1) cp arch/powerpc/configs/linkstation_defconfig .config

Make sure the config is sane: The default config is minimal. You'll have to enable support for any non-standard things you may be using. I use reiserfs and netatalk, so I enabled support for that filesystem and also for appletalk. Also, with recent filesystem developments, you may wish to consider ext4 or others.
 * 1) make ARCH=powerpc menuconfig

For troubleshooting ease, it is a good idea to enable Netconsole kernel access. Enable '''Device drivers -> Networking device support -> Network console logging support (EXPERIMENTAL) '''

Compile your kernel

 * 1) make uImage && make modules && make modules_install

Sit back and listen to music. Go to the store. Wash the dog.

Backup your old kernel and dtb file

 * 1) cp /boot/uImage /boot/uImage.bak
 * 2) cp /boot/kuroboxHG.dtb /boot/kuroboxHG.dtb.bak

If you have a LS1/HD, then change your .dtb filename as necessary.

Compile the dtb file

 * 1) cp kuroboxHG.dtb /tmp/
 * 2) cd /usr/src/linux/arch/powerpc/boot/dts
 * 3) dtc -I dts -O dtb -V 16 -o /tmp/kuroboxHG.dtb kuroboxHG.dts
 * 4) cp /tmp/kuroboxHG.dtb /boot/kuroboxHG.dtb

Install the kernel & enable modules

 * 1) cp /usr/src/linux/arch/powerpc/boot/uImage /boot/uImage
 * 2) cd /lib/modules/2.6.2x.x/
 * 3) depmod

Note: If your using the Gentoo 2007 Image, check that your Kernel Image name matches. Your kernel image may be called vmlinux.UBoot instead of uImage

Note: if your using Dave's lenny tarball you may need to check that the uImage symlink is pointing to your new kernel.

Reboot

 * 1) reboot

With any luck, you'll be booting your new kernel.

Watch your netconsole window for information that may prove helpful in case of a problem.

Troubleshooting
Give your box time to come up, it may take a while to boot after the upgrade.

If something goes wrong, simply boot in EM mode and copy your old kernel back.


 * 1) cp /boot/uImage.bak /boot/uImage
 * 2) cp /boot/kuroboxHG.dtb.bak /boot/kuroboxHG.dtb
 * 3) echo -n "OKOK" > /dev/fl3