How do I link a static lib to a yocto autotools project in Eclipse - eclipse

Question

I have created a Yocto autotools project in Eclipse (based on a Hello World project).
I wanted to separate my code into a number of libs and then link them in a form of static libs (.a) to my project.
Now I have one app and a number of static libs. However, no matter what I try I can't get my code to compile. Each separate lib compiles and produces a .a file, but my app doesn't.
After searching the web I have a possible solution - add a direct link to my static libs:
MyApp_CPPFLAGS="-I$LOCATION"
MyApp_LDADD="/home/xxx/workspace/MyApp/Encoding2/Debug/libEncoding2.a"
This is my Makefile.am file, where libEncoding2.a exist in that path.
The error I get is:
make[2]: *** No rule to make target `"/home/xxx/workspace/MyApp/Encoding2/Debug/libEncoding2.a"', needed by `MyApp'. Stop.
I already built the lib so I am not sure why a make try is even needed.
Any help will be appreciated.

Answer 1

Because you use static library in your recipes, you can make a soft link to the library in your project source folder, i.e., hello-world-0.1, using following command to link to your static library
ln -s /home/xxx/workspace/MyApp/Encoding2/Debug/libEncoding2.a
and then edit your bb file, hello-world_0.1.bb, adding the source path to your URL
SRC_URI = " \
file://libEncoding2.a \
file://hello-world.c \
"
and in the do_compile block, using follow command to compile your project
do_compile() {
${CC} hello-world.c libEncoding.a -o hello-world
}
do_install() {
install -d ${D}${bindir}/Hello
install -m 0755 enet ${D}${bindir}/Hello
}
After you bitbake your project
bitbake hello-world
and run mkefidisk.sh, you can find the hello-world in /usr/bin/Hello/hello-world. Hope this hint can help you.
BTW, I am not familiar with autotools, I just use make to bitbake the recipes. And your static library should also be created in Yocto not in Eclipse I think. So I think your path for the static library maybe not correct, it should locate in ~/yocto/build/tmp/... or some where like this. In my case, it was located in ln -s ~/yocto/build/tmp/sysroots/intel-corei7-64/usr/lib/libEncoding.a depends on your target environment.

Answer 2

Depending on whether you're using libtool or not, you should have either a noinst_LTLIBRARIES or noinst_LIBRARIES list of targets, respectively. This should only include the name of your library (libEncoding2.la or libEncoding2.a.)
You should never use a full path for this, and you should not quote Make variables, so what you were looking for is
MyApp_CPPFLAGS = -I$LOCATION
MyApp_LDADD = libEncoding2.la # or .a
And that would work.
But on the other hand it seems like you should take some time to understand how autotools work, as it might not be what you're looking for. With a grain of salt you can take my Autotools Mythbuster as a starting point.