Using the SDK
THIS IS THE OLD DOCUMENT
See Using the SDK for the latest version
The SDK is a relocatable, precompiled OpenWrt toolchain suitable to cross compile single userspace packages for a specific target without compiling the whole system from scratch.
Reasons for using the SDK are:
- Compile custom software for a specific release while ensuring binary and feature compatibility
- Compile newer versions of certain packages
- Recompile existing packages with custom patches or different features
Obtain SDK
You can either download an already compiled SDK, or compile it yourself by using the “make menuconfig” command.
Prerequisites
Please see Build system – Installation page how to install the needed software to build the packages on the SDK.
Note: On some hosts it is needed to install the ccache package
Download
You should find bz2-archives ready for download in the corresponding download directory:
- Stable SDK "Chaos Calmer (15.05.1)" → Platform → OpenWrt-SDK-<Platform>-for-linux-x86_64-gcc-<version>-linaro-uClibc-<version>.tar.bz2
- Legacy SDKs (Historic Releases), → Platform → OpenWrt-SDK-<Platform>-for-linux-x86_64-gcc-<version>-linaro-uClibc-<version>.tar.bz2
Package Feeds
After decompressing the SDK archive, edit the feeds.conf.default
file to download the needed package definitions
Usage
By default the SDK ships with no package definitions.
Makefiles for packages to compile must be checked out from the OpenWrt repository and placed into the package/
directory first.
Obtain Definitions
- Use the
./scripts/feeds update -a
command to obtain package definitions. - After the definitions have been updates, execute
./scripts/feeds install <packagename>
to prepare the package and its dependencies.
Compile Packages
After the Makefile is in place, the usual buildroot commands apply:
make package/example/download
- download the soures of examplemake package/example/prepare
- extract the sources, apply patches and download if necessarymake package/example/compile
- compile example, prepare and download if necessarymake package/example/clean
- clean the sourcecodemake package/index
- build a repository index to make the output directory usable as local opkg source
Some packages are built on host:
$ make package/example/host/{clean,compile} V=99 |
The common command to recompile a package example and enable verbose output is:
$ make package/example/{clean,compile} V=99 |
After the compilation is finished, the generated .ipk files are placed in the bin directory.
The output of make might contain WARNING: your configuration is out of sync. Please run make menuconfig, oldconfig or defconfig!
. That warning is misleading and wrong in the SDK case. Since everything is precompiled you cannot run oldconfig (see Why is the SDK configuration out of sync?).
Example: existing package
The example below rebuilds tmux.
$ ./scripts/feeds install tmux Installing package 'tmux' Installing package 'toolchain' Installing package 'ncurses' Installing package 'libevent2' Installing package 'openssl' Installing package 'zlib' Installing package 'ocf-crypto-headers' $ make package/tmux/download Collecting package info: done tmp/.config-package.in:36:warning: ignoring type redefinition of 'PACKAGE_libc' from 'boolean' to 'tristate' tmp/.config-package.in:64:warning: ignoring type redefinition of 'PACKAGE_libgcc' from 'boolean' to 'tristate' # # configuration written to .config # make[1] package/tmux/download make[2] -C feeds/packages/utils/tmux download $ make package/tmux/prepare tmp/.config-package.in:36:warning: ignoring type redefinition of 'PACKAGE_libc' from 'boolean' to 'tristate' tmp/.config-package.in:64:warning: ignoring type redefinition of 'PACKAGE_libgcc' from 'boolean' to 'tristate' # # configuration written to .config # make[1] package/tmux/prepare make[2] -C feeds/packages/utils/tmux prepare $ make package/tmux/compile tmp/.config-package.in:36:warning: ignoring type redefinition of 'PACKAGE_libc' from 'boolean' to 'tristate' tmp/.config-package.in:64:warning: ignoring type redefinition of 'PACKAGE_libgcc' from 'boolean' to 'tristate' # # configuration written to .config # make[1] package/tmux/compile make[2] -C feeds/base/package/libs/toolchain compile make[2] -C feeds/base/package/libs/ocf-crypto-headers compile make[2] -C feeds/base/package/libs/zlib compile make[2] -C feeds/base/package/libs/openssl compile make[2] -C feeds/base/package/libs/libevent2 compile make[2] -C feeds/base/package/libs/ncurses host-compile make[2] -C feeds/base/package/libs/ncurses compile make[2] -C feeds/base/package/libs/ncurses compile make[2] -C feeds/base/package/libs/ncurses compile make[2] -C feeds/packages/utils/tmux compile make[1] package/index make[1] package/index $ ls bin/ar71xx/packages/packages tmux_1.9a-1_ar71xx.ipk
Build your own packages
Troubleshooting
Some SDK versions have bugs.
Bug: BB SDK for BRCM2708: wants to compile with “ccache_cc” see https://dev.openwrt.org/ticket/13949
Bug: BB SDK for BRCM2708: static compilation broken