Cross compilation for gpsd shows "unrecognized option" - c++

I am cross-compiling gpsd3.20 on my Ubuntu 16.04 for the ARM architecture. As you may know, gpsd uses Sconsctruct to compile the source codes. During my cross-compilation, the moment when it needs to create the libgps.so it shows an error unrecognized option '-Wl, -Bsymbolic'.
Before posting the question here, I have tried t check my toolchain binaries and I found out that if I run this line manually:
sudo ./arm-v7a-linux-gnueabihf-ld -o test/gpsd-3.20/libgps.so.25.0.0 -pthread -shared -Wl,-Bsymbolic-functions -Wl,-soname=libgps.so.25 test/gpsd-3.20/os_compat.os test/gpsd-3.20/rtcm2_json.os test/rtcm3_json.os test/gpsd-3.20/shared_json.os test/gpsd-3.20/timespec_str.os test/gpsd-3.20/libgpsmm.os -L. -lrt -lm -lrt
The above commands print out the exact error as I mentioned previously. However, if I run the exact command replacing ld with gcc, then there is no any errors.
sudo ./arm-v7a-linux-gnueabihf-gcc -o test/gpsd-3.20/libgps.so.25.0.0 -pthread -shared -Wl,-Bsymbolic-functions -Wl,-soname=libgps.so.25 test/gpsd-3.20/os_compat.os test/gpsd-3.20/rtcm2_json.os test/rtcm3_json.os test/gpsd-3.20/shared_json.os test/gpsd-3.20/timespec_str.os test/gpsd-3.20/libgpsmm.os -L. -lrt -lm -lrt
Upon checking the arm-v7a-linux-gnueabihf-gcc --help, I found out that, gcc support -Wloptions whereas in the arm-v7a-linux-gnueabihf-ld it doesn't support the -Wl options. So now I am not sure how to change the SConstruct file so that it doesn't execute ld instead I want it to execute gcc especially for the libgps.so part.

(can't comment), so as answer: have you tried to set the env.-var.:
export LD=arm-v7a-linux-gnuabihf-gcc
Gcc takes -Wl,XXX and passes XXX to the linker.

I think you've got two combining problems here, though there's some guessing involved without looking into the build itself. First, scons shouldn't be adding the flag when building a library (https://github.com/SCons/scons/issues/3248 - fixed but, I believe, not part of a release). Second, "linking" should probably be done using gcc. If you call gcc to link, it still calls the linker behind the scenes - after dealing with options that are intended for gcc, which -Wl,-Bsymbolic is, it means pass -Bsymbolic on to the linking phase (indicated by -Wl, the 'l' meaning linker). So I'm supposing that the way you've told scons about the cross toolchain isn't quite right either, if it's calling ld directly you're probably going to have other issues as well.

Related

Compiling C++ with g++ -m32 option

I am trying to compile as this :
-bash-4.1$ g++ -static -m32 Hello.cpp
and getting errors like this:
/opt/rh/devtoolset-4/root/usr/libexec/gcc/x86_64-redhat-linux/5.2.1/ld: skipping incompatible /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.2.1/libstdc++.a when searching for -lstdc++
/opt/rh/devtoolset-4/root/usr/libexec/gcc/x86_64-redhat-linux/5.2.1/ld: cannot find -lstdc++
collect2: error: ld returned 1 exit status
I have tried this as well but still get the exact same error above:
g++ -static -m32 -L/opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.2.1/32 Hello.cpp
I have tried in both orders - nothing helps.
Why is it still looking at the wrong directory?
Is using -m32 option override -L option?
I could not find much documentation on -m32 option.
Please help.
Thanks!
Why is it still looking at the wrong directory?
Compiler always looking in predefined directories first. -L options adds your path to these list of directories, so because of it compiler is stil looking at the wrong directory. For more detailed output try to compiler your program with detailed output -### or -v options.
Is using -m32 option override -L option?
The answer is no - -m32 options is option to generate 32bit code, for example:
You may generate 32bit code that will work on 32bit machine, on your 64bit machine. Also you may run this code on your 64bit machine - it will work well.
I could not find much documentation on -m32 option.
Here is the link to the GCC docs
And here is doc about directory searching options
Also to say to compiler where to find libraries, you may set
LD_LIBRARY_PATH in your env
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$FULL_PATH_TO_YOUR_LIB
Do not override env vars - cause it may cause more problems if you are not absolutely sure in what you are doing.

Linking against a c/c++ library

I have some basic questions regarding linking against a C/C++ library. I am trying to understand the difference in using the two different usages -L/usr/local/lib -lm usage and /usr/local/lib/libm.a usage. E.g., when I compile and link an example from the [SUNDIALS] library, both of the following work
gcc -Wall cvRoberts_dns.c -o cvRoberts_dns.exe -I/usr/local/include -L/usr/local/lib/ -lsundials_cvode -lsundials_nvecserial -lm
OR
gcc -Wall cvRoberts_dns.c -o cvRoberts_dns.exe /usr/local/lib/libsundials_cvode.a /usr/local/lib/libsundials_nvecserial.a
However, to compile and link an example from the library [libsbml], the following works
g++ -Wall readSBML.cpp -o readSBML.exe -I/usr/local/include -L/usr/local/lib -lsbml
but the this does not
g++ -Wall readSBML.cpp -o readSBML.exe /usr/local/lib/libsbml.a
If required, I can post the complete error message I get, but the last line of the message is as follows
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
My questions are as follows:
In the second style of linking (of the first example), there is no information regarding where to find the include files (header files), how does the compiler know the information supplied in -I/usr/local/include which is provided in the first style of the first example?
In the second style of first example there is no /usr/local/lib/libm.a (it actually gives an error message that libm.a cannot be found if I try to include it), then why -lm is required in the first style?
How do I compile the second example in the second style (i.e., using /usr/local/lib/libsbml.a)? I do see that there are files - libsbml.a and libsbml-static.a in the /usr/local/lib folder, but none of them work.
If it helps, I am on an OS X machine.
I would be very thankful if any one could help in this regard.
Just an update - I tried
g++ -Wall readSBML.cpp -o readSBML.exe /usr/local/lib/libsbml.5.dylib
and that compiled and linked just fine.
Thanks
SN
In general
The -L option is meant to find where the libraries themselves are. Each library is a collection of one or more object code (machine language) files. There is no need to find the include files.
The -I option has nothing to with linker, it helps the compiler resolve the header files used in your driver programme( eg Roberts_dns.c). This happens during the pre-processing stage.
In the second style of linking (of the first example), there is no
information regarding where to find the include files (header files),..
If the compilation worked as you expected,it may be because /usr/local/include is in the default include path for gcc. To check the default include path for gcc do gcc -xc -E -v -.
In the second style of first example there is no
/usr/local/lib/libm.a(it actually gives an error message that libm.a
cannot be found if I try to include it), then why -lm is required in
the first style?
In Linux, some libraries like libc.a are directly linked to your execultable by default while libm.a is not. In Mac (your environment), though, libm is directly link to the executable by default. So you don't have to explicitly link it. It is less likely that libm.a is located in /usr/local/lib/. So you got an error. But why link it in the first place?

How to cope with older library installed in `/usr/lib` by sysadmin

I have recently got an account on a supercomputer grid, and I'm trying to compile my code in theri system. Problem is that program won't link with following errors:
/mnt/opt/tools/slc6/binutils/2.22/bin/ld: warning: libboost_system.so.1.55.0, needed by /mnt/home/jbzdak/tools/boost_1_55//lib/libboost_thread.so, may conflict with libboost_system.so.5
/mnt/opt/tools/slc6/binutils/2.22/bin/ld: /mnt/home/jbzdak/tools/boost_1_55//lib/libboost_thread.so: undefined reference to symbol '_ZN5boost6system15system_categoryEv'
/mnt/opt/tools/slc6/binutils/2.22/bin/ld: note: '_ZN5boost6system15system_categoryEv' is defined in DSO /mnt/home/jbzdak/tools/boost_1_55//lib/libboost_system.so.1.55.0 so try adding it to the linker command line
/mnt/home/jbzdak/tools/boost_1_55//lib/libboost_system.so.1.55.0: could not read symbols: Invalid operation
collect2: error: ld returned 1 exit status
Which is due to the fact that my program needs boost 1.55, and only 1.39 is instlled on the system in /usr/lib64. I have installed my version of boost in local folder, but somehow still system one is loaded first.
Here is excerpt from flags passed to the compiler:
-std=gnu++11 -Werror -Wall -lboost_thread -lboost_filesystem -lboost_system -lboost_iostreams -g -DG4OPTIMISE -Iinclude
-W -Wall -ansi -pedantic -Wno-non-virtual-dtor -Wno-long-long -Wwrite-strings -Wpointer-arith -Woverloaded-virtual -pipe -O2
full listing of flags is here (they should be irrevelant).
Here are revelant config variables:
LIBRARY_PATH /mnt/home/jbzdak/tools/boost_1_55/lib:
CPLUS_INCLUDE_PATH /mnt/home/jbzdak/tools/boost_1_55/include:/mnt/home/jbzdak/tools/geant4.9.6.3/compile/include/Geant4
LD_LIBRARY_PATH /mnt/home/jbzdak/tools/boost_1_55/lib:/mnt/opt/tools/slc6/gcc/4.8.3/lib64: ...
Directory /mnt/home/jbzdak/tools/boost_1_55 contains installed boost library.
I use GCC 4.8.3 with ld 2.22.
I have very little experience with linker errors hence the question. Is there any way to exclude boost libraries in /usr/lib64, or make the linker use locally installed libraries, and and ignore the system one?
I said in a comment:
There's no -L/alternative/location/of/boost/lib shown, so the compiler (linker) doesn't know it needs to look somewhere else for your modern Boost library. You may need -Wl,rpath,/alternative/location/of/boost/lib as well.
And the question was asked:
Why didn't LD_LIBRARY_PATH solve the issue?
Because LD_LIBRARY_PATH is a run-time variable rather than a link-time variable. It affects where the /lib/ld.so.1 (or equivalent) dynamic loader looks for libraries when you run a program, not where the linker looks to find its libraries.
After some additional debugging and asking another question, I found out the root cause of problem. Any -L parameter has precedence over LIBRARY_PATH and somehow -L/usr/lib64 was added (hence it had precedence over my version).
To check what options are sent to gcc pass -v parameter.

Facebook warpdrive build - D Programming language

Of late, facebook opensourced warp, C/C++ preprocessor.
https://github.com/facebook/warp
I'm trying to build it using dmd and stuck with some build errors.
I downloaded dmd.2.065.0.zip for dmd compiler - dmd2/linux/bin64/dmd
I also see a bunch of libraries, for example libphobos2.a
Then when I build warp, I see some errors from ld, that keep complaining that phobos2.a could not be found. I exported LD_LIBRARY_PATH to the dir where this library is stored but no luck.
I compiled in verbose mode, and it doesn't give more info.
Command:
/path/to//building_stuff/dmd2/linux/bin64/dmd -O -inline -release -ofwarp cmdline.d constexpr.d context.d directive.d expanded.d file.d id.d lexer.d loc.d macros.d main.d number.d outdeps.d ranges.d skip.d sources.d stringlit.d textbuf.d -v
Error excerpt:
function textbuf.Textbuf!char.Textbuf.length
function textbuf.Textbuf!char.Textbuf.resize
gcc warp.o -o warp -m64 -L/path/to/building_stuff/dmd2/linux/bin64/../lib64 -Xlinker --export-dynamic -l:libphobos2.a -lpthread -lm -lrt
/usr/bin/ld: cannot find -l:libphobos2.a
collect2: ld returned 1 exit status
--- errorlevel 1
I was hoping the D language experts here, or those who know about warp already could give me some hint.
I was not on CentOS, as warp demands. I wonder if that could anyway be the reason.
I was not using gcc 4.7.x as warp demands, but, to me, the library could just not be located doesn't look like a problem from old gcc I have.
I was on redhat5.5 machine with 4.1 gcc.
CentOS is basically a RedHat, so everything should work OK. As people commented, your real problem is the -l:libphobos2.a in your link line. Remember, GNU/Linux allows colons in file-names, so :libphobos2.a is a perfectly valid file, and GNU ld won't find it in the library search paths.
Note that they've added a make file to easy on your compilation, I managed to compile it using "make -j" and only editing the dmd command line in the make.
just rename "libphobos2.a" to "lib:libphobos2.a.a"
I faced a similar problem with ld version 2.17, but with version 2.20 this 'l:<libfilename>' kinda syntax works fine.

What does the gcc -R parameter do?

I am trying to run an autotools configure script for the bson-cpp project, and it fails because it cannot determine what flags it needs to compile with boost_filesystem. A quick look at confg.log shows:
g++ -o conftest -g -O2 -pthread -L/usr/local/lib -R/usr/local/lib -L/usr/local/libexec conftest.o -lboost_filesystem-mt -lboost_system-mt >&5
g++: error: unrecognized option '-R'
So, naturally, I tried to find out what the R option does, but I can't seem to find it documented anywhere. I've checked here and here to no avail. What does the option do and how do I tell autotools not to use it?
-R does not seem to be an option for g++ or gcc anywhere. -R may be a linker option on some platforms that is equivalent of -rpath to gnu ld, ... This seems to be a known bug in boost builds ... have a look at Use -Wl to pass arguments to the linker.
It actually has the patch available there
I am re-posting it for convenience, however PLEASE PLEASE look at the original URL linked above for official patch!
--- ../gnote/m4/boost.m4 2011-01-25 14:30:18.000000000 +0200
+++ m4/boost.m4 2011-02-27 20:57:11.686221539 +0200
## -403,7 +403,7 ##
LDFLAGS=$boost_save_LDFLAGS
LIBS=$boost_save_LIBS
if test x"$Boost_lib" = xyes; then
- Boost_lib_LDFLAGS="-L$boost_ldpath -R$boost_ldpath"
+ Boost_lib_LDFLAGS="-L$boost_ldpath -Wl,-R$boost_ldpath"
Boost_lib_LDPATH="$boost_ldpath"
break 6
else
It's an option similar to -rpath, but available only on some platforms. The script is maybe failing detecting your platform ?
It is not a valid option for GCC, so it does not do anything.
It is possibly a valid option for other compilers though, which could be why autoconf gives it a shot.
Not all errors in the config.log files are a problem. autoconf figures out a lot of things by "guessing", i.e. trying something and keeping that if it worked.