Kernel build instructions

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 Kernel will not be binary compatible with one that comes with firmware, meaning you'll need to rebuild all modules too, unless exact same toolchain and source code is used. See "Firmware Compatibility" section.


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. The 2011.03 does not work. 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:


The Kernel : 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:


Getting The Patches

You have to come back to your initial directory: 

cd ..

Then: 

git clone git://git.openpandora.org/pandora-oe-environment.git pandora-firmware
cd pandora-firmware
source ./op-env-oe.sh
./initial-setup.sh
cd metadata/openembedded.git/
git checkout op.openembedded.next


Applying The Patches

Now go back into the previously downloaded kernel sources : 

cd ../../../pandora-kernel/

And patch around: 

patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/0001-Add-EHCI-patch-suggested-by-Steven-Kipisz.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/0002-Add-missing-define-to-EHCI-OMAP.c.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/no-empty-flash-warnings.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/oprofile-0.9.3.armv7.diff
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/no-cortex-deadlock.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/read_die_ids.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/fix-install.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/mru-fix-timings.diff
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/mru-fix-display-panning.diff
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/mru-make-dpll4-m4-ck-programmable.diff
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/mru-improve-pixclock-config.diff
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/mru-make-video-timings-selectable.diff
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/mru-enable-overlay-optimalization.diff
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/dvb-fix-dma.diff
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/0001-Removed-resolution-check-that-prevents-scaling-when.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/0001-Implement-downsampling-with-debugs.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/musb-rxtx.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/squashfs/0006-SquashFS-Backport-SquashFS4-to-our-2.6.27-tree.patch
patch -p1 < ../pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/aufs2/0007-AUFS2-Add-latest-AUFS2-in-tree-code-for-2.6.27.patch


More Dirty Things

If you have "mixed implicit and normal rules" errors (make >= 3.82), edit the Makefile:

Remove the "config" at the beginning of the line 448.

Remove the "/" at the beginning of the line 1610.


If you have "cc1: error: unrecognized command line option "-mlittle-endian"", then your toolchain is probably too recent.


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:

DJWillis: 

export PATH=$PATH:/usr/local/angstrom/arm/bin

GS G++: 

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

You also need to have CROSS_COMPILE set (DJWillis): 

export CROSS_COMPILE=arm-angstrom-linux-gnueabi-

Or (GS G++): 

export CROSS_COMPILE=arm-none-linux-gnueabi-

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

export ARCH=arm

Now set copy the defconfig from the patch location : 

cp /wherever_it_is/pandora-firmware/metadata/openpandora.oe.git/recipes/linux/omap3-pandora-kernel/defconfig ./.config

If you want to customize kernel features, run 

make menuconfig

When finished, just run 

make uImage
make

OR (in case of errors with CS G++) : 

make CROSS_COMPILE="arm-none-linux-gnueabi-" uImage
make CROSS_COMPILE="arm-none-linux-gnueabi-" modules

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

And (almost) finally : 

cp arch/arm/boot/uImage /path/to/your/pandora/filesystem/boot/
INSTALL_MOD_PATH="/path/to/your/pandora/filesystem/" make modules_install

Building Wi-Fi modules

Come back to your main directory, then clone the Wi-Fi git: 

git clone git://openpandora.org/pandora-wifi.git
cd pandora-wifi
git checkout --track -b pandora-wifi

Build (change env variables if needed): 

export PATH=$PATH:/usr/local/angstrom/arm/bin/
export CROSS_COMPILE=arm-angstrom-linux-gnueabi-
make clean
make ARCH=arm KLIB=../pandora-kernel KLIB_BUILD=../pandora-kernel

And copy to your OP filesystem, ie if it's on /media/OS/ : 

mkdir -p /media/OS/lib/modules/2.6.27.46-omap1/updates/compat/
cp compat/*.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/compat/
chmod 0644 /media/OS/lib/modules/2.6.27.46-omap1/updates/compat/*.ko

mkdir -p /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/mac80211/
cp net/mac80211/*.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/mac80211/
chmod 0644 /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/mac80211/*.ko

mkdir -p /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/wireless/
cp net/wireless/*.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/wireless/
chmod 0644 /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/wireless/*.ko

mkdir -p /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/rfkill/
cp net/rfkill/*.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/rfkill/
chmod 0644 /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/net/rfkill/*.ko

mkdir -p /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/wl12xx/
cp drivers/net/wireless/wl12xx/wl1251.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/wl12xx/
cp drivers/net/wireless/wl12xx/wl1251_sdio.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/wl12xx/
chmod 0644 /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/wl12xx/wl1251*.ko

# some bonus not wl1251 related drivers

cp drivers/net/wireless/at76c50x-usb.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/
chmod 0644 /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/at76c50x-usb.ko

mkdir -p /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/rt2x00/
cp drivers/net/wireless/rt2x00/*.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/rt2x00/
chmod 0644 /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/rt2x00/*.ko

mkdir -p /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/p54/
cp drivers/net/wireless/p54/*.ko /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/p54/
chmod 0644 /media/OS/lib/modules/2.6.27.46-omap1/updates/kernel/drivers/net/wireless/p54/*.ko

First Boot

At the first boot, if modules don't load, type as root : 

depmod -ae

And reboot.


- One forum thread about kernel recompilation here:.

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