These are the scripts used to compile the ev3dev kernel. Originally it also included scripts to bootstrap a root file system and create a disk image. Those scripts have evolved into the brickstrap package.
- Debian or derivative OS (Ubuntu, Mint, etc.)
- User account with
sudo
enabled
build-kernel
Used to build the kernel.
defconfig
Used to manage the *_defconfig
file and
your current local configuration (.config
).
install-kernel-build-tools
Installs the prerequisite tools required
to build the kernel.
menuconfig
Runs the menu configuration tool for the
kernel configuration.
pbuilder-dist
Modified version of pbuilder-dist
from
ubuntu-dev-tools
package. Allow you to specify
architecture of rpi
to build packages for
Raspbian (amrv6).
-
If you don't have
git
already, then we need to install it.~ $ sudo apt-get install git
-
Create a working directory somewhere. For this tutorial, we are using
~/work
. The build scripts will generate extra subdirectories here so we suggest creating a new directory instead of using an existing one.~ $ mkdir work ~ $ cd work
-
Clone this repo and also the ev3-kernel repo, then make sure the lego drivers submodule is up to date (we don't always update the submodule commit in the kernel repo, so you have to pull manually to get the most recent commits).
~/work $ git clone git://github.com/ev3dev/ev3dev-buildscripts ~/work $ git clone --recursive git://github.com/ev3dev/ev3-kernel ~/work $ cd ev3-kernel/drivers/lego ~/work/ev3-kernel/drivers/lego $ git pull origin master ~/work/ev3-kernel/drivers/lego $ cd ../../..
-
Change to the
ev3dev-buildscripts
directory and have a look around.~/work $ cd ev3dev-buildscripts ~/work/ev3dev-buildscripts $ ls boot.cmd build-kernel install-kernel-build-tools local-env README.md build-boot-scr defconfig LICENSE menuconfig setup-env
-
Now we need to install the required tool. To do this, we need to add the ev3dev package repo and then run the
install-kernel-build-tools
script. (You only need to run this once.)~/work/ev3dev-buildscripts $ sudo apt-add-repository http://ev3dev.org/debian ~/work/ev3dev-buildscripts $ sudo apt-key adv --keyserver pgp.mit.edu --recv-keys 2B210565 ~/work/ev3dev-buildscripts $ sudo apt-get update ~/work/ev3dev-buildscripts $ ./install-kernel-build-tools
-
Create a
local-env
to make use of all of your processing power. See the Faster Builds and Custom Locations section below for more about this file.~/work/ev3dev-buildscripts $ echo "export EV3DEV_MAKE_ARGS=-j4" > local-env
-
Now we can compile the kernel.
~/work/ev3dev-buildscripts $ ./build-kernel
-
That's it! The uImage and kernel modules you just built are saved in
../dist
. You just need to copy the files to your already formatted SD card. For an easier way of getting the kernel on your EV3, see Sharing Your Kernel.~/work/ev3dev-buildscripts $ cd ./build-area/linux-ev3dev-ev3-dist ~/work/ev3dev-buildscripts/build-area/linux-ev3dev-ev3-dist $ cp uImage <path-to-boot-partition>/uImage ~/work/ev3dev-buildscripts/build-area/linux-ev3dev-ev3-dist $ sudo cp -r lib/ <path-to-file-system-partition>
By default the locations of the kernel source tree and the toolchain used to build the kernel are expected to be in certain directories relative to the ev3dev-buildscripts repo directory.
You can override these locations by creating a file called local-env
in the ev3dev-buildscripts directory or ~/.ev3dev-env
(in your home directory).
It should look like this:
#!/bin/sh
export EV3DEV_MAKE_ARGS=-j4
# override any EV3DEV_* variables from setup-env script.
#export EV3DEV_XXX=/custom/path
#export EV3DEV_MERGE_CMD="kdiff3 \$file1 \$file2"
#export EV3DEV_MERGE_CMD="meld \$file1 \$file2"
The -j4
is for faster builds. It allows make to compile files in
in parallel. You should replace 4 with the number of processor cores that
you want to devote to building the kernel.
You can use custom paths to make the build-kernel
script automatically
install the kernel and modules directly on the EV3! First, you need to
mount the EV3 root file system. You can use nfs or sshfs (check the
wiki on how to do this). Then just set the appropriate paths in your
local-env
like this:
# replace `/mnt/ev3dev-root` with your actual mount point
export EV3DEV_INSTALL_KERNEL=/mnt/ev3dev-root/boot/flash
export EV3DEV_INSTALL_MODULES=/mnt/ev3dev-root
When you run ./build-kernel
if no existing kernel configuration exists
the default configuration is loaded from arch/arm/configs/ev3dev_defconfig
.
If you make changes to your local kernel configuration that you want to merge
into the default configuration, run ./defconfig update
. It will use the
merge tool specified by the EV3DEV_MERGE_CMD
environment variable.
If you have an existing kernel configuration, you will want to check for changes
to the default configuration each time you merge or checkout a branch. You can
call ./defconfig load
to wipe out your local configuration and load the
default configuration or you can call ./defconfig merge
to merge the
default configuration into your existing local configuration.
If you are forgetful or lazy or just want this to happen automatically, you can
set up hooks in your git repo. For example, you could save the following file as
both .git/hooks/post-merge
and .git/hooks/post-checkout
and you will
be prompted to merge the default configuration into your local configuration
whenever you merge or checkout a branch. In you followed the tutorial above,
<path-to-ev3dev-buildscripts-repo>
would be ~/work/ev3dev-buildscripts
.
#!/bin/sh
<path-to-ev3dev-buildscripts-repo>/defconfig merge
Want to send your custom kernel to someone so that they can use it? Never fear, there is an easy way to do that - using Debian packaging.
First, we want to set a kernel option so that our friends will know what kernel
they are running. Run ./menuconfig
and set this option:
General setup --->
(-your-name-ev3) Local version - append to kernel release
Make sure to include the '-' prefix in -your-name
on the Local version.
And, of course, substitute something like your github user name for your-name.
It is also important that the kernel release ends with -ev3
so that
flash-kernel
will recognize it as a "good" kernel and install it automatically.
Then, we build a Debian package.
~/work/ev3dev-buildscripts $ ./build-kernel deb-pkg KDEB_PKGVERSION=1
...
<lots-of-build-output>
...
~/work/ev3dev-buildscripts $ ls ../*.deb
../linux-headers-3.16.7-ckt9-5-ev3dev-your-name-ev3_1_armel.deb
../linux-image-3.16.7-ckt9-5-ev3dev-your-name-ev3_1_armel.deb
../linux-libc-dev_1_armel.deb
Now, send the linux-image-*
file to your friend with these instructions:
- Copy the
.deb
file to your EV3 - Install the package
- Reboot the EV3
Example:
user@host ~ $ scp linux-image-*.deb otheruser@ev3dev:~
user@host ~ $ ssh otheruser@ev3dev
otheruser@ev3dev:~$ sudo dpkg --install ~/linux-image-*.deb
otheruser@ev3dev:~$ sudo reboot
-
If you see this error...
ERROR: ld.so: object 'libfakeroot-sysv.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS64): ignored.
...just ignore it. It is normal (a side effect of cross-compiling).
-
If you see an error related to
asm/bitsperlong.h
like this:... Generating include/generated/mach-types.h CC kernel/bounds.s In file included from /home/user/ev3-kernel/arch/arm/include/asm/types.h:4:0, from /home/user/ev3-kernel/include/linux/types.h:4, from /home/user/ev3-kernel/include/linux/page-flags.h:8, from /home/user/ev3-kernel/kernel/bounds.c:9: /home/user/ev3-kernel/include/asm-generic/int-ll64.h:11:29: fatal error: asm/bitsperlong.h: No such file or directory compilation terminated. make[2]: *** [kernel/bounds.s] Error 1 make[1]: *** [prepare0] Error 2 make: *** [sub-make] Error 2
Then you need to clean your kernel source tree like this:
user@host ~/ev3-kernel $ git clean -dfX
There are a few changes needed to build the rpi-ev3dev kernel.
-
You need to install some additional packages:
sudo apt-get install rpi-mkimage gcc-linaro-arm-linux-gnueabihf-raspbian
-
You need to clone the
rpi-kernel
repository instead of theev3-kernel
repository.git clone git://github.com/ev3dev/rpi-kernel
-
You need to set the
RPI
environment variable to1
or2
depending on which model you are compiling for when calling any of the scripts.Example:
RPI=1 ./build-kernel
-
If you add a local version to the kernel release (as you should be doing), the last bit needs to be
-rpi
or-rpi2
instead of-ev3
.