Tag Archive: cross compiler

So you have U-Booted your Zipit Z2?  Great!  Now you are ready to exploit one of the biggest advantages of moving from blob to U-boot…  Building your own kernel.

First off, you need to have built a cross-compiler of some sort to build the kernel.  I have posted directions for my version here in my post about building U-Boot for the Z2.  After that, you will need to make sure u-boot-tools is installed on your system.  On Gentoo you can use portage to install it but you will need to unmask the package.  To unmask that package on Gentoo, add ACCEPT_KEYWORDS=”~x86″ to your /etc/make.conf.  Then type “emerge u-boot-tools”.

Next, download the latest version of the Zipit kernel from here:


To start off, I’m going to use Mozzwald’s suggested .config file.  You will need to rename it .config and put it in the base directory of your kernel.  Next, replace the <base_kernel_dir>/arch/arm/mach-pxa/z2.c with a bleeding edge one if desired.  Mozzwald and Sweetlilmre both have been diligently hacking away at that file so you could ask in the irc.freenode.net #zipit-dev channel to obtain the latest version or use this z2.c for now.

Now for the fun stuff.  You can use a make menuconfig command as follows to add your own customizations to the kernel:

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- menuconfig

Now it’s time to build the new kernel:

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j9 uImage

Now, if you built a modular kernel, you will need to build the modules and stick them somewhere:

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- modules
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- INSTALL_MOD_PATH=/where/to/drop/modules modules_install

After this is done, your new kernel should be sitting there for you ready to go in the arch/arm/boot directory and your modules are wherever you put them.  Just copy the uImage and modules to the appropriate locations on your Zipit’s SD card and you will be good to go.

Since there is no central repository for fresh U-Boot binaries for the Zipit Z2, I decided to build my own u-boot.bin from source.  Before I could do this, I needed to build a cross compiler for the arm processor.  This is something I’ve always had trouble with on Debian systems but this time I used Gentoo and everything worked flawlessly.  Luckily Marex left me with some very helpful hints on how to get the job done.  First, you’ll need to set up a cross compiler if you have not already:

emerge crossdev

You’ll need to add the following lines to your /etc/make.conf:


Don’t forget to make the following directory since that is where your new tool chain is going to live:

mkdir /usr/local/portage

Now it’s time to build your tool chain.  This will take quite a bit of time.

time crossdev -S -t arm-linux-gnueabi

After all of that, you should be ready to build your u-boot.bin.  First you need to grab the latest snapshot from http://git.denx.de/?p=u-boot/u-boot-pxa.git;a=shortlog;h=refs/heads/devel.  Go ahead and unpack the file in your home directory:

tar -xvf u-boot-pxa-*

cd u-boot-pxa

Next you need to run the following command.  Double check and make certain that you have a space between the “…gnueabi-” and the “zipitz2…” parts.

make CROSS_COMPILE=arm-linux-gnueabi- zipitz2_config

Lastly, you can build the u-boot.bin firmware file with this command:

make CROSS_COMPILE=arm-linux-gnueabi-

You should now have a working u-boot.bin file in the ./u-boot-pxa directory.  With that file, you can follow these instructions to upgrade U-boot on your Zipit Z2.  As usual, thanks to Marex for giving me the proper hints to make this happen.

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