Compiling on OpenWRT: Difference between revisions

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***Install the full version of BASH: opkg install bash

*Environment variables to add;

**export LDFLAGS="-Wl,-rpath=/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib"

**export LDFLAGS="-Wl,-rpath=/usr/lib:/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib (the DD-WRT / Entware version: export LDFLAGS="-Wl,-rpath=/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib", needs to be modified for OpenWRT)

***needs to be adjusted for OpenWRT

***-WI is a switch that allows for additional items to be added via the GNU [https://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_node/ld_3.html LD] (https://stackoverflow.com/questions/6562403/i-dont-understand-wl-rpath-wl) command

****OpenWRT -rpath ~~equivalent is~~ /~~usr~~/lib ~~instead of DD~~-~~WRT's~~ /opt/lib

***-rpath in LDLFLAGS = "-rpath=/usr/lib:/opt/lib" is the same as executing this on the command line: export LD_LIBRARY_PATH = "/opt/lib

****Path for /opt/~~include:~~

****rpath AND/OR <code>LD_LIBRARY_PATH</code> is a path used by an executable program to search directories containing shared libraries after the program has been compiled (from https://en.wikipedia.org/wiki/Rpath and https://stackoverflow.com/questions/4250624/ld-library-path-vs-library-path)

***-WI is a switch that allows for additional items to be added via [https://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_node/ld_3.html LD] (https://stackoverflow.com/questions/6562403/i-dont-understand-wl-rpath-wl)

****OpenWRT has its own equivalent path, which is /usr/lib, however there are some variations in files and sizes. Solution? Include both paths;

*****-rpath=/usr/lib:/opt/lib (this will search OpenWRT's /usr/lib directory first, then DD-WRT / Entware's /opt/lib directory second)

***--dynamic-linker

****For DD-WRT / Entware it is located here: /opt/lib/ld-linux.so.3, which is a symbolic link to ld-2.27.so (and here too: /lib/gcc/arm-openwrt-linux-gnueabi/7.4.0)

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****<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)

****

***~~-rpath in LDLFLAGS = "-rpath=/opt/lib" is the same as: export LD_LIBRARY_PATH = "/opt/lib (rpath is for run time (not compile time) libraries, https://en.wikipedia.org/wiki/Rpath)~~

*****

****<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)

****OpenWRT has its own equivalent path, which is /usr/lib, however there are some variations in files and sizes. Solution? Include both paths;

*****-rpath=/usr/lib:/opt/lib (this will search OpenWRT's /usr/lib directory first, then DD-WRT / Entware's /opt/lib directory second)

**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"

@@ Line 18: / Line 18: @@
 ***Install the full version of BASH: opkg install bash
 *Environment variables to add;
-**export LDFLAGS="-Wl,-rpath=/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib"
+**export LDFLAGS="-Wl,-rpath=/usr/lib:/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib (the DD-WRT / Entware version: export LDFLAGS="-Wl,-rpath=/opt/lib -Wl,--dynamic-linker=/opt/lib/ld-linux.so.3 -L/opt/lib", needs to be modified for OpenWRT)
-***needs to be adjusted for OpenWRT
+***-WI is a switch that allows for additional items to be added via the GNU [https://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_node/ld_3.html LD] (https://stackoverflow.com/questions/6562403/i-dont-understand-wl-rpath-wl) command
-****OpenWRT -rpath equivalent is /usr/lib instead of DD-WRT's /opt/lib
+***-rpath in LDLFLAGS = "-rpath=/usr/lib:/opt/lib" is the same as executing this on the command line: export LD_LIBRARY_PATH = "/opt/lib
-****Path for /opt/include:
+****rpath AND/OR <code>LD_LIBRARY_PATH</code> is a path used by an executable program to search directories containing shared libraries after the program has been compiled (from https://en.wikipedia.org/wiki/Rpath and https://stackoverflow.com/questions/4250624/ld-library-path-vs-library-path)
-***-WI is a switch that allows for additional items to be added via [https://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_node/ld_3.html LD] (https://stackoverflow.com/questions/6562403/i-dont-understand-wl-rpath-wl)
+****OpenWRT has its own equivalent path, which is /usr/lib, however there are some variations in files and sizes.  Solution?  Include both paths;
+*****-rpath=/usr/lib:/opt/lib (this will search OpenWRT's /usr/lib directory first, then DD-WRT / Entware's /opt/lib directory second)
 ***--dynamic-linker
 ****For DD-WRT / Entware it is located here: /opt/lib/ld-linux.so.3, which is a symbolic link to ld-2.27.so (and here too: /lib/gcc/arm-openwrt-linux-gnueabi/7.4.0)
@@ Line 31: / Line 32: @@
 ****<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)
 ****
-***-rpath in LDLFLAGS = "-rpath=/opt/lib" is the same as: export LD_LIBRARY_PATH = "/opt/lib (rpath is for run time (not compile time) libraries, https://en.wikipedia.org/wiki/Rpath)
+*****
-****<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)
-****OpenWRT has its own equivalent path, which is /usr/lib, however there are some variations in files and sizes.  Solution?  Include both paths;
-*****-rpath=/usr/lib:/opt/lib (this will search OpenWRT's /usr/lib directory first, then DD-WRT / Entware's /opt/lib directory second)
 **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"