Why can't GCC cross compiler find all libraries? - c++

Question

Why does it look for libgcc in the library search paths, but not for the crt*.o libraries (scroll down in the second code block below)? Also, why is it looking in /lib and /usr/lib under the sysroot, but not in /tmptools/lib under the sysroot (which is the only path that I actually want it to look in)? This is how the cross compiler was configured:
../binutils-2.26/configure --prefix="$LFS_CROSSTOOLCHAIN" --build=$LFS_BUILD_ARCH --host=$LFS_BUILD_ARCH --target=$LFS_TARGET_ARCH --with-lib-path="/tmptools/lib" --disable-multilib --disable-multiarch --disable-rpath --disable-nls --with-sysroot="$LFS_SYSROOT"
../gcc-6.1.0/configure --prefix="$LFS_CROSSTOOLCHAIN" --build=$LFS_BUILD_ARCH --host=$LFS_BUILD_ARCH --target=$LFS_TARGET_ARCH --disable-bootstrap --with-newlib --without-headers --with-local-prefix="/tmptools" --with-native-system-header-dir="/tmptools/include" --with-lib-path="/tmptools/lib" --disable-multilib --disable-multiarch --disable-rpath --enable-languages=c,c++ --disable-nls --with-sysroot="$LFS_SYSROOT"
Where LFS_CROSSTOOLCHAIN=/home/main/lfs/3/crosstools and LFS_SYSROOT=/home/main/lfs/3/root.
This is example output:
$ 3/crosstools/bin/x86_64-lfs-linux-gnu-gcc -print-sysroot
/home/main/lfs/3/root
$ 3/crosstools/bin/x86_64-lfs-linux-gnu-ld -print-sysroot
/home/main/lfs/3/root
$ 3/crosstools/bin/x86_64-lfs-linux-gnu-gcc -Wl,--verbose test.c
GNU ld (GNU Binutils) 2.26.20160125
Supported emulations:
elf_x86_64
elf32_x86_64
elf_i386
elf_iamcu
i386linux
elf_l1om
elf_k1om
using internal linker script:
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==================================================
attempt to open crt1.o failed
attempt to open crti.o failed
attempt to open crtbegin.o failed
attempt to open /tmp/ccLVBgXQ.o succeeded
/tmp/ccLVBgXQ.o
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libgcc.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libgcc.a failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libgcc.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libgcc.a failed
attempt to open /home/main/lfs/3/root/lib/libgcc.so failed
attempt to open /home/main/lfs/3/root/lib/libgcc.a succeeded
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libgcc_s.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libgcc_s.a failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libgcc_s.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/root/lib/libgcc_s.so failed
attempt to open /home/main/lfs/3/root/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/root/usr/lib/libgcc_s.so failed
attempt to open /home/main/lfs/3/root/usr/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib64/libgcc_s.so failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib64/libgcc_s.a failed
attempt to open /tmptools/lib/libgcc_s.so failed
attempt to open /tmptools/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib/libgcc_s.so failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libc.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libc.a failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libc.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libc.a failed
attempt to open /home/main/lfs/3/root/lib/libc.so failed
attempt to open /home/main/lfs/3/root/lib/libc.a failed
attempt to open /home/main/lfs/3/root/usr/lib/libc.so failed
attempt to open /home/main/lfs/3/root/usr/lib/libc.a failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib64/libc.so failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib64/libc.a failed
attempt to open /tmptools/lib/libc.so failed
attempt to open /tmptools/lib/libc.a failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib/libc.so failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib/libc.a failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libgcc.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libgcc.a failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libgcc.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libgcc.a failed
attempt to open /home/main/lfs/3/root/lib/libgcc.so failed
attempt to open /home/main/lfs/3/root/lib/libgcc.a succeeded
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libgcc_s.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/libgcc_s.a failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libgcc_s.so failed
attempt to open /home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/root/lib/libgcc_s.so failed
attempt to open /home/main/lfs/3/root/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/root/usr/lib/libgcc_s.so failed
attempt to open /home/main/lfs/3/root/usr/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib64/libgcc_s.so failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib64/libgcc_s.a failed
attempt to open /tmptools/lib/libgcc_s.so failed
attempt to open /tmptools/lib/libgcc_s.a failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib/libgcc_s.so failed
attempt to open /home/main/lfs/3/root/home/main/lfs/3/crosstools/x86_64-lfs-linux-gnu/lib/libgcc_s.a failed
attempt to open crtend.o failed
attempt to open crtn.o failed
/home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/bin/ld: cannot find crt1.o: No such file or directory
/home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/bin/ld: cannot find crti.o: No such file or directory
/home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/bin/ld: cannot find crtbegin.o: No such file or directory
/home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/bin/ld: cannot find -lgcc_s
/home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/bin/ld: cannot find -lc
/home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/bin/ld: cannot find -lgcc_s
/home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/bin/ld: cannot find crtend.o: No such file or directory
/home/main/lfs/3/crosstools/lib/gcc/x86_64-lfs-linux-gnu/6.1.0/../../../../x86_64-lfs-linux-gnu/bin/ld: cannot find crtn.o: No such file or directory
collect2: error: ld returned 1 exit status

Answer 1

When I built a GCC toolchain for cross-compiling ARM, I used this helpful tutorial. The errors you are seeing look similar to what happens if you skip these commands:
make -j4 csu/subdir_lib
install csu/crt1.o csu/crti.o csu/crtn.o /opt/cross/aarch64-linux/lib
Which are part of a sequence of commands used to provide the headers for GLIBC to the cross-compiler.
mkdir -p build-glibc
cd build-glibc
../glibc-2.20/configure --prefix=/opt/cross/aarch64-linux --build=$MACHTYPE
--host=aarch64-linux --target=aarch64-linux \
--with-headers=/opt/cross/aarch64-linux/include \
--disable-multilib libc_cv_forced_unwind=yes
make install-bootstrap-headers=yes install-headers
make -j4 csu/subdir_lib
install csu/crt1.o csu/crti.o csu/crtn.o /opt/cross/aarch64-linux/lib \
aarch64-linux-gcc -nostdlib -nostartfiles -shared -x c /dev/null -o \
/opt/cross/aarch64-linux/lib/libc.so
touch /opt/cross/aarch64-linux/include/gnu/stubs.h
cd ..
It's unclear if the GLIBC headers are already in your sysroot directory, but I would start by checking to make sure those files exist. You may need to build the GLIBC headers if you are not getting them some other way.