Setting Up Cross-Compile Environment for Omega
This tutorial will walk you through setting up the OpenWRT Cross-Compile environment on a Ubuntu Linux system.
Step 1: Setup OpenWRT Buildroot Environment
Install tools and library sources:
$ apt-get install -y subversion build-essential libncurses5-dev zlib1g-dev gawk flex quilt git-core unzip libssl-dev
Step 2: Get OpenWRT Source
$ git clone git://git.openwrt.org/15.05/openwrt.git $ cd openwrt
Step 3: Update Feeds
Feeds are repositories of packages that can be added to the OpenWRT system. Feeds are configured in the feeds.conf.default file. Additional feeds can be added by editing this file. For example, to add the Onion packages, append the following line to the file:
src-git onion https://github.com/OnionIoT/OpenWRT-Packages.git
feeds.conf.default file, and update the feeds:
$ scripts/feeds update -a
This will fetch all the repositories configured in the
To install a package to the source we are about to compile, for example:
$ scripts/feeds install python
This downloads python to our source code tree, but doesn’t compile the package by default.
Step 4: Modify Image
Files in the
package/base-file/files directory will be overwritten to the compiled image at the end of the compilation process. To add custom files to the compiled image, create a files folder in the buildroot directory. Files in this directory will supersede the files in the
Step 5: Select Packages
As mentioned, packages installed are not selected by default when compiling the image, and will not appear in the final firmware. To select packages to be compiled into the image:
$ make menuconfig
ENTER to enter into a category. To exit to previous menu press
ESC twice. To toggle the selection state of packages press
First ensure the following:
- Target System is Atheros AR7xxx/AR9xxx
- Subtarget is Generic
- Target Profile is Onion Omega
- Target Images is squashfs
Different markings on packages represent their selection state.
< > are unselected;
<*> are selected;
<M> are selected to compile as modules (i.e. compiled as Opkg packages, but not included in the image by default);
-*- are dependencies required by other package(s).
Selection state can be toggled using
N for unselected,
Y for selected, and
M for module.
When package selection is finished, exit out of menuconfig by pressing
ESC twice. When prompted whether to save changes, select
Step 6a: Compile Image
Start the compile process:
On multi-core systems, add the
-j flag to take advantage of additional cores:
$ make -jn
where n is the number of cores (
nproc) + 1.
To enable verbose mode:
$ make V=s
Once the compile is complete, binaries are found in the
openwrt-ar71xx-generic-onion-omega-squashfs-factory.bin is the full image, and
openwrt-ar71xx-generic-onion-omega-squashfs-sysupgrade.bin is the image for system upgrade.
Compiled Opkg packages are found in the
Step 6b: Compile Individual Packages
Compiling the entire image can take a long time depending on the system. Luckily, individual packages can be compiled without needing to compile the whole image.
First, we need to build the toolchain to compile and package the binaries (this is typically done by make automatically when building the image, and it only needs to be done once):
$ make tools/install $ make toolchain/install
Now you can compile the individual package:
$ make package/<package name>/compile
<package name> needs to be substituted for the package in question. Also note that if this package has dependencies, they must be compiled first using the same command.
Finally, if you decide the newly compiled package should be installed into the image:
$ make package/<package name>/install
will install it into the image that you have already created.
Finally, if you wish to generate the index for the package:
$ make package/index
This is typically done automatically by make to keep an updated list of packages installed in the image.
Step 7: Flash Image
On the Omega,
# cd /tmp
This is done because
/tmp is a RAM disk that has enough storage to download the image to be flashed.
Download the image:
# wget https://downloads.onion.io/openwrt-ar71xx-generic-onion-omega-squashfs-factory.bin
Once the image is downloaded, start the flash process:
# sysupgrade openwrt-ar71xx-generic-onion-omega-squashfs-factory.bin
If you wish the system to try to preserve modified files in
/etc directory, where most of the configuration is kept, add the
# sysupgrade -c openwrt-ar71xx-generic-onion-omega-squashfs-factory.bin
If you wish to overwrite all configuration changes and restore the original image setting, add the
# sysupgrade -n openwrt-ar71xx-generic-onion-omega-squashfs-factory.bin