Kernel build instructions

Preparation

First you need a toolchain and several other tools.

Cygwin (Windows Users)

Cygwin is a Linux-like environment for Windows; download and install here. You will need additional packages installed to build the kernel:

• diffutils
• gcc4
• make
• ncurses
• libncurses-devel
• git (see below)

CodeSourcery G++

Usually CodeSourcery's ARM GNU/Linux tool chain is used to build OMAP3 kernels, but other variations can be used as well. For CodeSourcery, 2009q1-203 version is recommended (click "all versions" in above page), as 2007q3 doesn't work with kernels above 2.6.29, and 2008q1-2008q3 produce bad code in some situations. See BeagleBoard page for more information.

Windows Users: When installing on Windows, do not use the default install path, as it contains spaces and will cause problems when building (when the build system uses -print-file-name=include). Install to

C:\SourceryG++\

or similar. As mentioned here, create an environment variable called CYGPATH with the value 'cygpath' (minus the quotes). Patching your install using the SourceryG++ guide to kernel building as a reference is necessary to get your cygwin/windows builds off the ground.

Git

For source control access, you need to have git installed. Use your packet manager or build it from source. On Windows, install via cygwin.

A guide for basic git usage.

mkimage

Finally you need to have 'mkimage' tool in PATH, which can be built as part of u-boot build process, or download below:

• mkimage - linux version
• mkimage - windows version

Cloning and switching branches

Now you need to 'clone' kernel source using git tools from previous step. Make a directory you want to keep source in and cd into it. Then run:

git clone git://openpandora.org/pandora-kernel.git

This will now download the source from openpandora.org. Note that it will take a while, so be patient. When done, you will have default 'master' branch checked out, but it doesn't have the latest files, so you need to checkout the current 'pandora-27-omap1' branch:

cd pandora-kernel/

Then:

git checkout --track -b pandora-27-omap1 origin/pandora-27-omap1

Firmware Compatibility

The firmware kernel is built using OE (openembedded), so the only sure way to get binary compatibility is to use that (see Firmware_build_instructions).

The manual procedure to do the same without using OE would be:

• Get DJWillis' toolchain (it is the same as one built by OE).
• Apply the patches listed in recipes/linux/omap-pandora-kernel_2.6.27-pandora.bb from the git repository at git://git.openpandora.org/openpandora.oe.git on the kernel tree. musb-rxtx.patch may not apply cleanly unless you remove the junk at the end and fix the context for musbhsdma.c
• Copy the defconfig file from above patches location to .config
• Set up environment as described in "Building" section and build (make/make uImage).

Building

To build you need to have several environment variables set. If you don't have your toolchain in PATH, you need to add it there:

export PATH=$PATH:/path/to/arm-2009q1/bin

You also need to have CROSS_COMPILE set:

export CROSS_COMPILE=arm-none-linux-gnueabi-

Newer kernels (2.6.3x+) need ARCH set to arm:

export ARCH=arm

Now set up the default .config file:

make omap3_pandora_defconfig

If you want to customize kernel features, run

make menuconfig

When finished, just run

make uImage
make

and it should build you uImage and place it in arch/arm/boot/ . You can now use it to boot from SD card (recommended) or replace the one in your flash. Last make command will build you kernel modules.