Difference between revisions of "Compiling on OpenWRT"
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These are some notes, we'll see if it works and warrants a full article... | These are some notes, we'll see if it works and warrants a full article... | ||
* Entware has better resources documentation for compiling on a router: https://github.com/Entware/Entware/wiki/Using-GCC-for-native-compilation | *Entware has better resources documentation for compiling on a router: https://github.com/Entware/Entware/wiki/Using-GCC-for-native-compilation | ||
* A key resource are headers; | *A key resource are headers; | ||
** To keep OpenWRT and Entware stuff separate, create the /opt directory: mkdir /opt | **To keep OpenWRT and Entware stuff separate, create the /opt directory: mkdir /opt | ||
** Then it is safe to install / download this: wget -qO- <nowiki>http://bin.entware.net/armv7sf-k3.2/include/include.tar.gz</nowiki> | tar xvz -C /opt/include | **Then it is safe to install / download this: wget -qO- <nowiki>http://bin.entware.net/armv7sf-k3.2/include/include.tar.gz</nowiki> | tar xvz -C /opt/include | ||
* And from this source, it is easy to add the path when compiling: https://gcc.gnu.org/onlinedocs/cpp/Search-Path.html | *And from this source, it is easy to add the path when compiling: https://gcc.gnu.org/onlinedocs/cpp/Search-Path.html | ||
** By default, gcc searches these directories first: /usr/include and /usr/lib/gcc/arm-openwrt-linux-muslgnueabi/7.4.0/include | **By default, gcc searches these directories first: /usr/include and /usr/lib/gcc/arm-openwrt-linux-muslgnueabi/7.4.0/include | ||
** Downloading the above Entware Header File, this command can be used to search a different directory, like /opt/include, first: -I''WhatEverDirectory'' | **Downloading the above Entware Header File, this command can be used to search a different directory, like /opt/include, first: -I''WhatEverDirectory'' | ||
* Items to install; | *Items to install; | ||
** Make: https://man7.org/linux/man-pages/man1/make.1.html | **Make: https://man7.org/linux/man-pages/man1/make.1.html | ||
*** opkg install gcc make | ***opkg install gcc make | ||
** Entware recommends installing the following: opkg install busybox ldd make gawk sed (a version of ldd and sed are included within the OpenWRT version of BusyBox) | **Entware recommends installing the following: opkg install busybox ldd make gawk sed (a version of ldd and sed are included within the OpenWRT version of BusyBox) | ||
** Additional utilities are recommended | **Additional utilities are recommended | ||
*** Install the full version of BASH: opkg install bash | ***Install the full version of BASH: opkg install bash | ||
* Environment variables to add; | *Environment variables to add; | ||
** export LDFLAGS="-Wl,-rpath=/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib", but... (rpath is for run time (not compile time) libraries, https://en.wikipedia.org/wiki/Rpath) | **export LDFLAGS="-Wl,-rpath=/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib", but... (rpath is for run time (not compile time) libraries, https://en.wikipedia.org/wiki/Rpath) | ||
*** needs to be adjusted for OpenWRT (/usr/lib) instead of DD-WRT (/opt/lib) | ***needs to be adjusted for OpenWRT (/usr/lib) instead of DD-WRT (/opt/lib) | ||
* | ***LDLFLAGS = "-L/opt/include" is the same as: export LIBRARY_PATH=/opt/include (https://gcc.gnu.org/onlinedocs/gcc/Environment-Variables.html) | ||
****<code>LIBRARY_PATH</code> is used by gcc before compilation to search directories containing static and shared libraries that need to be linked to your program (from https://stackoverflow.com/questions/4250624/ld-library-path-vs-library-path) | |||
***LDLFLAGS = "-rpath=/opt/lib" is the same as: export LD_LIBRARY_PATH = "/opt/lib | |||
** LDLFLAGS = "-L/opt/include" is the same as: export LIBRARY_PATH=/opt/include (https://gcc.gnu.org/onlinedocs/gcc/Environment-Variables.html) | ****<code>LD_LIBRARY_PATH</code> is used by your program to search directories containing ''shared'' libraries after it has been successfully compiled and linked (from https://stackoverflow.com/questions/4250624/ld-library-path-vs-library-path) | ||
*** <code>LIBRARY_PATH</code> is used by gcc before compilation to search directories containing static and shared libraries that need to be linked to your program | **export CFLAGS="-O2 -pipe -march=armv7-a -mtune=cortex-a9 -fno-caller-saves -mfloat-abi=soft ", but... | ||
** LDLFLAGS = "-rpath=/opt/lib" is the same as: export LD_LIBRARY_PATH = "/opt/lib | ***...but because this is OpenWRT, not DD-WRT, add an item to the end of it: export CFLAGS="-O2 -pipe -march=armv7-a -mtune=cortex-a9 -fno-caller-saves -mfloat-abi=soft -I/opt/include" | ||
*** <code>LD_LIBRARY_PATH</code> is used by your program to search directories containing ''shared'' libraries after it has been successfully compiled and linked. | ***CFLAGS = "-I/opt/include" is the same as: export CPATH=/opt/include (https://gcc.gnu.org/onlinedocs/cpp/Environment-Variables.html | ||
Revision as of 15:07, 19 October 2020
These are some notes, we'll see if it works and warrants a full article...
- Entware has better resources documentation for compiling on a router: https://github.com/Entware/Entware/wiki/Using-GCC-for-native-compilation
- A key resource are headers;
- To keep OpenWRT and Entware stuff separate, create the /opt directory: mkdir /opt
- Then it is safe to install / download this: wget -qO- http://bin.entware.net/armv7sf-k3.2/include/include.tar.gz | tar xvz -C /opt/include
- And from this source, it is easy to add the path when compiling: https://gcc.gnu.org/onlinedocs/cpp/Search-Path.html
- By default, gcc searches these directories first: /usr/include and /usr/lib/gcc/arm-openwrt-linux-muslgnueabi/7.4.0/include
- Downloading the above Entware Header File, this command can be used to search a different directory, like /opt/include, first: -IWhatEverDirectory
- Items to install;
- Make: https://man7.org/linux/man-pages/man1/make.1.html
- opkg install gcc make
- Entware recommends installing the following: opkg install busybox ldd make gawk sed (a version of ldd and sed are included within the OpenWRT version of BusyBox)
- Additional utilities are recommended
- Install the full version of BASH: opkg install bash
- Make: https://man7.org/linux/man-pages/man1/make.1.html
- Environment variables to add;
- export LDFLAGS="-Wl,-rpath=/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib", but... (rpath is for run time (not compile time) libraries, https://en.wikipedia.org/wiki/Rpath)
- needs to be adjusted for OpenWRT (/usr/lib) instead of DD-WRT (/opt/lib)
- LDLFLAGS = "-L/opt/include" is the same as: export LIBRARY_PATH=/opt/include (https://gcc.gnu.org/onlinedocs/gcc/Environment-Variables.html)
LIBRARY_PATHis used by gcc before compilation to search directories containing static and shared libraries that need to be linked to your program (from https://stackoverflow.com/questions/4250624/ld-library-path-vs-library-path)
- LDLFLAGS = "-rpath=/opt/lib" is the same as: export LD_LIBRARY_PATH = "/opt/lib
LD_LIBRARY_PATHis used by your program to search directories containing shared libraries after it has been successfully compiled and linked (from https://stackoverflow.com/questions/4250624/ld-library-path-vs-library-path)
- export CFLAGS="-O2 -pipe -march=armv7-a -mtune=cortex-a9 -fno-caller-saves -mfloat-abi=soft ", but...
- ...but because this is OpenWRT, not DD-WRT, add an item to the end of it: export CFLAGS="-O2 -pipe -march=armv7-a -mtune=cortex-a9 -fno-caller-saves -mfloat-abi=soft -I/opt/include"
- CFLAGS = "-I/opt/include" is the same as: export CPATH=/opt/include (https://gcc.gnu.org/onlinedocs/cpp/Environment-Variables.html
- export LDFLAGS="-Wl,-rpath=/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib", but... (rpath is for run time (not compile time) libraries, https://en.wikipedia.org/wiki/Rpath)