Basic tutorial guide, memo. for OpenWRT.

1. OpenWRT
Basic tutorial guide, memo.
by Antony.Wu
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2. OpenWRT builtroot
• It is a set of Makefiles and patches that allows users to generate
a cross-toolchain and a root filesystem for embeded system.
• It generates cross-compiler toolchain and use the toolchain to
build an image for your target board, such as AR-5387un router.
• It can also download packages (feeds), patches (using quilt) it
for you.
• # make toolchain/gdb/prepare QUILT=1
• <modify files in build_dir/>
• # make toolchain/gdb/updatevim
• It has modified make targets: component/name/action.
• # make toolchain/gdb/compile V=s
• V=s means “Verboase = stdout/stderror”
• # make toolchain/gdb/clean V=s
2
V=?
s standard output/error
w shows only warning

3. 3
Get OpenWRT buildroot
Main repositories and feeds
− # git clone git://git.openwrt.org/openwrt.git
− # git clone git://git.openwrt.org/packages.git
Barrier Breaker
− # git clone git://git.openwrt.org/14.07/openwrt.git
− # git clone git://git.openwrt.org/14.07/packages.git
− # svn co -r 42990
svn://svn.openwrt.org/openwrt/branches/barrier_bre
aker

4. 4
Setup OpenWRT environment
Using Fedora distribution, you need the following
package ready.
− # yum install -y subversion binutils bzip2 gcc gcc-c++ gawk
gettext flex ncurses-devel zlib-devel make patch unzip perl-
ExtUtils-MakeMaker glibc glibc-devel glibc-static quilt
ncurses-lib sed sdcc intltool sharutils bison wget
Check environment variables
− # echo $SED # must be empty, or issue '# unset SED'
− # echo $GREP_OPTIONS # don't contain '--initial-tab'
Set the PATH:
− PATH=$PATH:<buildroot dir>/staging_dir/host/bin
− PATH=$PATH:<buildroot dir>/staging_dir/toolchain-
<platform>-<gcc_ver>-<libc_ver>/bin

5. 5
Understand OpenWRT Feeds
It is a set of packages, like a ‘yum repo’, or ‘apt-get repo’ on
desktop linux.
 The script downloads the packages info into ‘feeds/’ .
 The script installs packages into ‘package/feeds/’
 Packages in feeds selectable by CONFIG_PACKAGE_xxxx in .config
file.
The repo is configured in the feeds.conf or feeds.conf.default
(such as yum repo configured in /etc/yum.repos.d)
A script is used to control those packages
 # ./scripts/feeds update -a
 Package index (information) will be stored into feeds/
 # ./scripts/feeds install <package_name>
 Src will be checkouted into package/feeds/<package_name>

6. OpenWRT Make
• Clean
• # make clean # rm -rf bin build_dir
• # make dirclean # rm -rf bin build_dir staging_dir toolchain logs
• # make distclean # all above, rm all downloaded packages and .config
• Ignore errors
• #IGNORE_ERRORS=1 make <make options>
• component/name/action.
• Clean Linux objects
• # make target/linux/clean V=s
• Clean package luci.
• # make package/luci/clean
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7. OpenWRT Make sequence
1. # make tools/install
2. # make toolchain/install
3. # make target/compile
4. # make package/cleanup
5. # make package/compile
6. # make package/install
7. # make package/preconfig
8. # make target/install
9. # make package/index
You can issue them, one by
one, in order, so that you
can check and debug
each step.
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8. Create OpenWRT package
• Special Makefile template.
• Please refer to BuildPackage variables
PKG_NAME:=broadcom-wl
PKG_VERSION:=5.10.56.27.3
PKG_RELEASE:=5
PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION)_$(ARCH).tar.bz2
PKG_SOURCE_URL:=http://downloads.openwrt.org/sources
…
…
$(eval $(call KernelPackage,brcm-wl))
$(eval $(call KernelPackage,brcm-wl-mini))
$(eval $(call BuildPackage,wlc))
$(eval $(call BuildPackage,wl))
$(eval $(call BuildPackage,nas))
• BuildPackage only takes one argument directly – the
name of the package to be built, in this case “wlc".
# ls -l package/broadcom-wl/
files # default config.
Makefile
patches # patches from diff
src # source code
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9. Create OpenWRT package 2
• BuildPackage define ‘Package/’
• The following describe the ‘define’ you may need:
define Package/broadcom-wl/Default
<action>
endef
• Package/description : description
• Package/conffiles : config-files installed by this pkg.
• Build/Prepare (optional): How to unpack/patch src.
• Build/Configure (optional) : How to configure src.
• Build/Compile (optional) : How to compile src.
• Build/InstallDev (optoinal) : Lib. needed
• Please refer to BuildPackage defines
Note: ‘define’ in makefile is like
‘=‘ operator.
Define the action when calling
‘Package/broadcom/wl/Default ‘
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10. Create OpenWRT package 3
• Override Build option
• Autoconf
• Eg. CONFIGURE_VARS += ac_cv_header_regex_h=no
• Eg. CONFIGURE_ARGS += --disable-native-affinity
• Compiler flags
• Eg. TARGET_CFLAGS+= -Wall
• Make
• Eg. MAKE_VARS = CFLAGS="$(TARGET_CFLAGS) $(EXTRA_CFLAGS)
$(TARGET_CPPFLAGS) $(EXTRA_CPPFLAGS)" …
• Eg. MAKE_FLAGS = $(TARGET_CONFIGURE_OPTS) CROSS="$
(TARGET_CROSS)" ARCH="$(ARCH)“
• CMake and Scons
• CMAKE_OPTIONS, CMAKE_HOST_OPTIONS
• SCONS_VARS
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11. Create OpenWRT package 4
• Adding configuration options
• Add MENU:=1
• Add Config.in Package/<name>/config
Makefile:
define Package/mjpg-streamer/config source
"$(SOURCE)/Config.in“
endef
Config.in:
menu "Configuration" depends on PACKAGE_mjpg-streamer
config MJPEG_STREAMER_AUTOSTART
bool "Autostart enabled" default n
• How to check your configuration
Makefile:
ifeq ($(CONFIG_MJPEG_STREAMER_INPUT_UVC),y)
$(CP) $(PKG_BUILD_DIR)/input_uvc.so $(1)/usr/lib
endif
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12. Create OpenWRT package 5
• Working on local application source
• Using feeds to tracking your state-of-the-art
work.
# ln -s /path/to/local/awesome_app_tree/.git feeds/my_cool_feed/awesome_app/git-src
# make package/awesome_app/{clean,compile} V=s
• Using USE_SOURCE_DIR
# make package/awesome_app/clean V=s
# make package/awesome_app/prepare USE_SOURCE_DIR=~/src/awesome_src V=s
# make package/awesome_app/clean V=s
• make prepare needs to be run every time
• make package/awesome_app/{clean,compile}
USE_SOURCE_DIR=~blah doesn't work
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13. OpenWRT kernel package

Adding configuration options

Add .mk file
#vim package/kernel/modules/block.mk
define KernelPackage/loop
SUBMENU:=$(BLOCK_MENU)
TITLE:=Loopback device support
KCONFIG:= CONFIG_BLK_DEV_LOOP CONFIG_BLK_DEV_CRYPTOLOOP=n
FLES:=$(LINUX_DIR)/drivers/block/loop.ko
AUTOLOAD:=$(call AutoLoad,30,loop)
endef
$(eval $(call KernelPackage,loop))
 Announce to build system.
# touch package/kernel/linux/Makefile

Add a kernel module that is not part of kernel
distribution
 Please refer to ‘package/madwifi/Makefile’ 13

14. What’s in the following slides?
1. # make tools/install
2. # make toolchain/install
3. # make target/compile
4. # make package/cleanup
5. # make package/compile
6. # make package/install
7. # make package/preconfig
8. # make target/install
9. # make package/index
You can issue them, one by
one, in order, so that you
can check and debug
each step.
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15. External Toolchain
 Compile everything with the target board,
you will have a dir named toolchain, called
build1

Copy the .config-file from the build1 and
make menuconfig.
[*] Advanced configuration options (for developers)
[*] Use external toolchain
Target name: arm-openwrt-linux-uclibcgnueabi (in my case, yours may vary)
Toolchain prefix: arm-openwrt-linux-uclibcgnueabi- (mind the dash at the end)
Toolchain root: /path/to/toolchain/staging_dir/toolchain-arm_v5te_gcc-
linaro_uClibc-0.9.32_eabi
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16. Alter download procedure

$DL_DIR is the location for download

Through "include/download.mk“

Init in “rules.mk”

To share downloaded packages

Put them in a shared location /opt/…

Check them in download procedure “define
Download” in file “download.mk”

MEMO: we can use shell to do this.

Eg . test -e /opt/dl/$(FILE) && ln -s /opt/dl/$(FILE) $(DL_DIR)/$(FILE) || (
$(if $(DownloadMethod/$(call dl_method,$(URL),$(PROTO))),$
(DownloadMethod/$(call dl_method,$(URL),$(PROTO))),$
(DownloadMethod/unknown)) )
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17. What has been added?
dl/ # for downloaded src.
build_dir/ # source code location
├── host
├── target-mips_mips32_uClibc-0.9.33.2
└── toolchain-mips_mips32_gcc-4.8.3_uClibc-0.9.33.2
logs/ # for compile logs
├── target
├── toolchain
└── tools
staging_dir/ # built out binary files.
├── host
├── target-mips_mips32_uClibc-0.9.33.2
└── toolchain-mips_mips32_gcc-4.8.3_uClibc-0.9.33.2
tmp/
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18. What’s in the following slides?
1. # make tools/install
2. # make toolchain/install
3. # make target/compile
4. # make package/cleanup
5. # make package/compile
6. # make package/install
7. # make package/preconfig
8. # make target/install
9. # make package/index
You can issue them, one by
one, in order, so that you
can check and debug
each step.
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19. Add our own BSP in target

The makefile in target will go into each
subdir.

Create a dir <BSP> of yours in the target dir.

Create a Makefile contains the following target.
all, download, prepare,
compile, install, clean

This also apply to the general ruls
 Eg # make target/<BSP>/prepare
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20. Reference
1. http://wiki.openwrt.org/doc/start
2. http://wiki.openwrt.org/about/toolchain
3. http://wiki.openwrt.org/doc/devel/packages
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