To compile the AIOS kernel as well as u-boot and x-load, you can either use OpenEmbedded and cross-compile it thanks to the kernel recipe, or download directly the sources and compile it with an external cross-compiler.
Download an external cross-compiler
You can typically use the toolchain from CodeSourcery available here
Following the instructions provided, you will typically end up with the following toolchain available on your machine:
arm-none-linux-gnueabi-addr2line arm-none-linux-gnueabi-ar arm-none-linux-gnueabi-as arm-none-linux-gnueabi-c++ arm-none-linux-gnueabi-c++filt arm-none-linux-gnueabi-cpp arm-none-linux-gnueabi-g++ arm-none-linux-gnueabi-gcc arm-none-linux-gnueabi-gcc-4.3.3 arm-none-linux-gnueabi-gcov arm-none-linux-gnueabi-gdb arm-none-linux-gnueabi-gprof arm-none-linux-gnueabi-ld arm-none-linux-gnueabi-nm arm-none-linux-gnueabi-objcopy arm-none-linux-gnueabi-objdump arm-none-linux-gnueabi-ranlib arm-none-linux-gnueabi-readelf arm-none-linux-gnueabi-size arm-none-linux-gnueabi-sprite arm-none-linux-gnueabi-strings arm-none-linux-gnueabi-strip
You will also need the mkimage command, so be sure it's installed on your host machine. On Ubuntu, you can install it with:
sudo apt-get install uboot-mkimage
Download the sources
Get the 2011-03.a AIOS version based on the 2.6.32 Linux kernel.
Note that the source code here contains the initramfs.cpio.gz file at the top of the tree, which is necessary to have the initramfs populated. This file is generated when building the ai-initramfs-image.
Extract and compile the code
Once downloaded the tgz files, expand them in your working directory and build everything. The CROSS_COMPILE argument must be filled with the prefix of your toolchain (ensure you have it in your PATH, or then pass the full path to the make command).
mkdir ai-kernel cd ai-kernel tar xzvf ai-kernel-2.6.32.tgz make CROSS_COMPILE=arm-none-linux-gnueabi- ARCH=arm uImage
Use the kernel on your SD card
Once compiled, you just need to copy the uImage built file on the first partition of your SD card. Assuming the first partition of your SD card is under /media/disk/:
cp arch/arm/boot/uImage /media/disk/ sync
To get a full working first partition on your SD card, you must have all the necessary files:
mlo u-boot.bin uImage uImage2 ai-ui.tbz2 ai-install.tbz2
Note that ai-install.tbz2 is required only for advanced reinstall features. In particular if you just want to try your own rootfs, you just need the four first files. In any case, be sure the mlo file is the first one copied on your first partition, otherwise the system will not boot.To have a full understanding of the process, we highly recommend to read the install script.