The project I am attempting compile is not in any way complex, and references nothing but the standard library and one self-contained library (everything compiles fine on another system). As indicated by the title, it can't even link against something in the standard library, due to things in there not having been compiled with -fPIC, supposedly. I didn't build it myself, nor do I want to, and reinstalling things with apt didn't seem to resolve the "recompile with -fPIC" issue.
I will say that I think one possible source of the issue is due to gcc-multilib or something being installed earlier, but I think that was purged. I don't know, maybe something was overwritten or a conflict arose. Might not even be related. Any ideas?
Running Ubuntu 18.04
g++ -I inc -I /usr/include/mono-2.0 -MMD -MF dep/Nonsense.d -std=c++17 -O3 -fno-stack-protector -fno-unroll-loops -fomit-frame-pointer -Wno-ignored-optimization-argument -c -o obj/Nonsense.o src/Nonsense.cpp
g++ -I inc -I /usr/include/mono-2.0 -MMD -MF dep/Socket.d -std=c++17 -O3 -fno-stack-protector -fno-unroll-loops -fomit-frame-pointer -Wno-ignored-optimization-argument -c -o obj/Socket.o src/Socket.cpp
g++ -shared -flto -o libNonsense.so obj/Nonsense.o obj/Socket.o -Llib -lenet
/usr/bin/x86_64-linux-gnu-ld: obj/Socket.o: relocation R_X86_64_PC32 against symbol `_ZTISt13runtime_error##GLIBCXX_3.4' can not be used when making a shared object; recompile with -fPIC
/usr/bin/x86_64-linux-gnu-ld: final link failed: Bad value
collect2: error: ld returned 1 exit status
makefile:22: recipe for target 'libNonsense.so' failed
make: *** [libNonsense.so] Error 1
Apparently, it is compulsory to compile with the -fPIC flag in 64bits platform. If you are making a 32-bits project with linkink with 32-bits library; you don't need -fPIC.
Indeed, without -fPIC, the dynamic linker recalculates adresses for global variables and functions (which are not known in advance in the step of compilation). However, in a 64-bits system, it is not possible to use this technique as it is required to guess in advance the size of adress.
PIC (Position Independent Code), a more sophisticated and complicated process is used. https://eli.thegreenplace.net/2011/11/11/position-independent-code-pic-in-shared-libraries-on-x64 for explanations.
As the error message says, you need to recompile with -fPIC. Your current compiler command does not show the -fPIC option:
g++ -I inc -I /usr/include/mono-2.0 -MMD -MF dep/Socket.d -std=c++17 -O3 -fno-stack-protector -fno-unroll-loops -fomit-frame-pointer -Wno-ignored-optimization-argument -c -o obj/Socket.o src/Socket.cpp
Same for -flto by the way—this flag also has to be specified when compiling in order to be effective.
Related
I am trying to compile libedit on linux using GCC 5.3 and am getting a cryptic error message.
/home/mybin/libgcc/x86_64-unknown-linux-gnu/5.3.0/../../../libcurses.a(lib_termcap.o): relocation R_X86_64_32 against `_nc_globals' can not be used when making a shared object; recompile with -fPIC
/home/mybin/lib/gcc/x86_64-unknown-linux-gnu/5.3.0/../../../libcurses.a: could not read symbols: Bad value
To what does the recompile with -fPIC refer, ncurses or libedit? and then how do I pass the -fPIC flag. I have tried adding CFLAGS=-fPIC to the configure of ncurses & libedit but still did not work.
I have found may posts on SO about what -fPIC is, but none on how to set the flag.
thanks Art
Perhaps you ran afoul of the changes outlined in Fedora's Changes/Harden All Packages which use a linker spec that only works if you have compiled using either -fPIC or -fPIE. The linker message is almost useless; only the part about -fPIC has any usefulness.
To address this problem, you can add/modify the compiler flags in several ways. One of the simplest is to set it in the CFLAGS environment variable, e.g.,
export CFLAGS='-O -fPIC'
If you happen to be building ncurses, this means that you would have to also be configuring to build only shared libraries, e.g.,
configure --with-shared --without-normal --without-debug
Of course that all works best if you do not have a previous set of makefiles, etc.
You're looking at the wrong part of the error message. The "relocation R_X86_64_32" means that you're trying to build 32-bit code against a 64-bit library or vice versa. Make sure you have selected the same architecture for both.
-fPIC is used to generate position independent code, it is used to create shared libraries. the make file has a problem, to fix it:
edit the Makefile, line 98 :
.c.o:
${CC} ${CFLAGS} -c $<
after CC add -fpic after CC like this :
.c.o:
${CC} -fpic ${CFLAGS} -c $<
also in line 103:
libedit.so: ${OOBJS}
${CC} --shared -o $# ${OOBJS}
add -fpic after --shared:
libedit.so: ${OOBJS}
${CC} --shared -fpic -o $# ${OOBJS}
if you are wondering what is the difference between -fPIC and -fpic note that they both do the same thing but -fpic is more efficient, check this for more informations What is the difference between `-fpic` and `-fPIC` gcc parameters?.
I facing some trouble compiling my programming assignment on my local machine. The program is distribute to us with makefiles and compilation commands that are known to work on the school's Scientific Linux servers. My local machine is Mac OS X El Capitan.
When I compile my program running make on my Mac, I get the following error that prevents compilation from proceeding:
myid-MacBook-Pro:mp6 myid$ make
gcc -g -lm -std=c99 -Wall -Werror -c lodepng.c
clang: error: -lm: 'linker' input unused
make: *** [lodepng.o] Error 1
But when I push that very same code as work in progress to the Linux servers and compile there, everything works fine. The linux servers use gcc and not clang:
[netid#linux-a2 mp6]$ make
gcc -g -lm -std=c99 -Wall -Werror -c functions.c
gcc -g -lm -std=c99 -Wall -Werror main.o lodepng.o imageData.o functions.o -o mp6 -lm
gcc -g -lm -std=c99 -Wall -Werror -c test.c
gcc -g -lm -std=c99 -Wall -Werror test.o lodepng.o imageData.o functions.o solution.o -o test -lm
In the makefile, these are the variable definitions:
CC=gcc
CFLAGS=-g -lm -std=c99 -Wall -Werror
and the target definition for loadpng.o
lodepng.o: lodepng.c
$(CC) $(CFLAGS) -c lodepng.c
I would appreciate any help on understanding this error and overcoming it.
Thank you very much.
Also, on this note, I thought I would say that I've noticed a subtle difference between Clang and GCC. It seems to me that even warnings generated by Clang would prevent the compilation to proceed so the warnings behaves like errors. But for GCC, if it generates warnings, it still compiles the object file. Please correct me if I'm mistaken.
Right now you're getting a compilation error on your Mac because you're trying to pass linker commands (i.e. -lm) into a compilation(i.e. -c). Do not give link flags when you compile (-c flag) your source files.
In the other compilation snippet you provided, the unused linker command seems to pass by unnoticed which isn't a good thing.
For your last question, the flag -Werror should force all compilation warnings to become errors -- which is exactly what you are describing.
I have an error making a code project because of what I believe is a missing routine from lapack:
HomographyInit.cc:(.text+0x385): undefined reference to `dgesvd_'
I think I need to add lapack library somehow to my Makefile. Here is part of my Makefile:
CC = g++
COMPILEFLAGS = -I MY_CUSTOM_INCLUDE_PATH -D_LINUX -D_REENTRANT -Wall -O3 -march=nocona -msse3
LINKFLAGS = -L MY_CUSTOM_LINK_PATH -lGVars3 -lcvd
I tried doing the following to no avail:
CC = g++
COMPILEFLAGS = -I MY_CUSTOM_INCLUDE_PATH -D_LINUX -D_REENTRANT -Wall -O3 -march=nocona -msse3
LINKFLAGS = -L MY_CUSTOM_LINK_PATH -lGVars3 -lcvd **-llapack**
Result:
make
...
/usr/bin/ld: cannot find -llapack
collect2: ld returned 1 exit status
How can I add lapack to my project? I am pretty sure I installed it correctly, though would be willing to double-check that somehow.
It looks like liblapack isn't in the path that ld can find. I would suggest two things:
Establish a symbolic link manually. It is possible (and sometimes common) that ld cannot recognize liblapack.so.3gf or liblapack.so.3.0.1 or so are essentially liblapack.so. You can set up a link by ln -s liblapack.so.3gf liblapack.so
Install liblapack-dev package instead if you're using ubuntu or debian repos. For some unclear reasons, liblapack3gf is not the same as liblapack-dev. I am not sure if in any circumstances, both will do or not do the same thing.
I think the first item should be able to resolve your problem (hopefully).
On my computer the dynamic library is in /usr/lib64/liblapack.so.3.4.1 and contains the requested symbol:
$ nm -D /usr/lib64/liblapack.so.3.4.1 | grep dgesvd
0000000000189200 T dgesvd_
So I would guess that the place where your lapack is installed is not in the linker search path. You should add the flag -L/path/to/the/lapackdir to LINKFLAGS
I'm trying to install GHC with -fPIC support in Fedora.
I've grabbed a source tarball since it seems no binary one has this.
In Build.mk i've changed the quick build type to
ifeq "$(BuildFlavour)" "quick"
SRC_HC_OPTS = -H64m -O0 -fasm -fPIC
GhcStage1HcOpts = -O -fasm -fPIC
GhcStage2HcOpts = -O0 -fasm -fPIC
GhcLibHcOpts = -O -fasm -fPIC
SplitObjs = NO
HADDOCK_DOCS = NO
BUILD_DOCBOOK_HTML = NO
BUILD_DOCBOOK_PS = NO
BUILD_DOCBOOK_PDF = NO
endif
unfortunately, when compiling i still get the ld error
ghc -fglasgow-exts --make -shared -oHs2lib.a /tmp/Hs2lib924498/Hs2lib.hs dllmain.o -static -fno-warn-deprecated-flags -O2 -package ghc -package Hs2lib -i/home/phyx/Documents/Haskell/Hs2lib -optl-Wl,-s -funfolding-use-threshold=16 -optc-O3 -optc-ffast-math
Linking a.out ...
/usr/bin/ld: /tmp/Hs2lib924498/Hs2lib.o: relocation R_X86_64_32 against `ghczmprim_GHCziUnit_Z0T_closure' can not be used when making a shared object; recompile with -fPIC
/tmp/Hs2lib924498/Hs2lib.o: could not read symbols: Bad value
So it seems that GHC-prim still isn't compiled with -FPIC
I've also told cabal to build any packages with -fPIC and shared.
Anyone have any ideas?
EDIT:
Thanks to dcouts I've been able to make some progress. But now i'm at the point where I thnk libffi isn't compiled with -fPIC. I've edited the makefile(.in) for it but so far, no luck.
The new command is:
ghc -fPIC -shared dllmain.o Hs2lib.o /usr/local/lib/ghc-7.0.3/libHSrts.a -o Hs2lib.so
where dllmain.c and Hs2lib.hs have both been compiled using -fPIC.
The error I get is:
/usr/bin/ld: /usr/local/lib/ghc-7.0.3/libHSffi.a(closures.o): relocation R_X86_64_32
against `.rodata' can not be used when making a shared object; recompile with -fPIC
/usr/local/lib/ghc-7.0.3/libHSffi.a: could not read symbols: Bad value
collect2: ld returned 1 exit status
After you see this error, do the following:
cd /tmp/Hs2lib924498/
ghc -fglasgow-exts --make -shared -oHs2lib.a /tmp/Hs2lib924498/Hs2lib.hs dllmain.o -static -fno-warn-deprecated-flags -fPIC -O2 -package ghc -package Hs2lib -i/home/phyx/Documents/Haskell/Hs2lib -optl-Wl,-s -funfolding-use-threshold=16 -optc-O3 -optc-ffast-math
Note I added -fPIC to the failed ghc command.
Once the command succeeds, continue the compilation from within the tmp directory without cleaning already compiled files. It should skip them and continue where it ended.
There's an FAQ entry on this topic on the Haskell Stack page.
It basically says the problem is environment related and sometimes non-deterministic.
The issue may be related to the use of hardening flags in some cases, specifically those related to producing position independent executables (PIE).
There's also a work around suggestion for Arch Linux:
On Arch Linux, installing the ncurses5-compat-libs package from AUR resolves this issue.
I am facing below errors when trying to statically link libDuma, Can you tell me how to ask g++ to use malloc from libDuma?
sunny#sunny-laptop:~/CodeTest$ g++ ./testDuma.cpp -g -o testDuma -static -lduma -pthread
/usr/lib/gcc/i686-linux-gnu/4.4.5/../../../../lib/libc.a(malloc.o): In function `free':
(.text+0x4b00): multiple definition of `free'
/usr/lib/gcc/i686-linux-gnu/4.4.5/../../../../lib/libduma.a(duma.o):(.text+0x25f0): first defined here
/usr/lib/gcc/i686-linux-gnu/4.4.5/../../../../lib/libc.a(malloc.o): In function `malloc':
(.text+0x4bc0): multiple definition of `malloc'
/usr/lib/gcc/i686-linux-gnu/4.4.5/../../../../lib/libduma.a(duma.o):(.text+0x2730): first defined here
/usr/lib/gcc/i686-linux-gnu/4.4.5/../../../../lib/libc.a(malloc.o): In function `realloc':
(.text+0x5950): multiple definition of `realloc'
/usr/lib/gcc/i686-linux-gnu/4.4.5/../../../../lib/libduma.a(duma.o):(.text+0x23d0): first defined here
collect2: ld returned 1 exit status
Don't force a completely static link (don't use the -static flag) -- doing so on any modern UNIX system is an extremely bad idea(TM).
Instead, link just the libduma statically. Either of these commands should work:
g++ ./testDuma.cpp -g -pthread -o testDuma /path/to/libduma.a
g++ ./testDuma.cpp -g -pthread -o testDuma -Wl,-Bstatic -lduma -Wl,-Bdynamic
Add -nodefaultlibs flag to not link to libc. Or, remove -lduma and link it dynamically after compilation with:
LD_PRELOAD=/usr/lib/libduma.so ./testDuma