crt1.o error in mips cross compiler

Question

I would like to generate MIPS binaries using gcc on an x86 machine. In order to install MIPS cross-compiler I followed the directions on this page. I could install gcc and binutils successfully. I tried to to compile a simple hello world program using the cross compiler.

/opt/cross/bin/mipsel-unknown-linux-gnu-gcc -mips1 hi.c 

I got the following error.

/opt/cross/lib/gcc/mipsel-unknown-linux-gnu/4.8.2/../../../../mipsel-unknown-linux-gnu/bin/ld: cannot find crt1.o: No such file or directory
/opt/cross/lib/gcc/mipsel-unknown-linux-gnu/4.8.2/../../../../mipsel-unknown-linux-gnu/bin/ld: cannot find crti.o: No such file or directory
/opt/cross/lib/gcc/mipsel-unknown-linux-gnu/4.8.2/../../../../mipsel-unknown-linux-gnu/bin/ld: cannot find -lc
/opt/cross/lib/gcc/mipsel-unknown-linux-gnu/4.8.2/../../../../mipsel-unknown-linux-gnu/bin/ld: cannot find crtn.o: No such file or directory
collect2: error: ld returned 1 exit status

I did some research online to figure out what the problem was, and changed the command I used to the following.

/opt/cross/bin/mipsel-unknown-linux-gnu-gcc -B/usr/lib/i386-linux-gnu -mips1 hi.c

Now I get this error message:

/opt/cross/lib/gcc/mipsel-unknown-linux-gnu/4.8.2/../../../../mipsel-unknown-linux-gnu/bin/ld: /usr/lib/i386-linux-gnu/crt1.o: Relocations in generic ELF (EM: 3)
/usr/lib/i386-linux-gnu/crt1.o: error adding symbols: File in wrong format
collect2: error: ld returned 1 exit status

I am not sure what the problem is. The only thing I can think of is the "--without-headers" option passed to configure program when building gcc. Configure command for gcc given on the linux-mips page is as below.

% ../gcc-3.8.2/configure --target=$TARGET --prefix=$PREFIX \
  --enable-languages=c --without-headers \
  --with-gnu-ld --with-gnu-as \
  --disable-shared --disable-threads \
  --disable-libmudflap --disable-libgomp \
  --disable-libssp --disable-libquadmath \
  --disable-libatomic

I would appreciate some help. The system on which I generated the cross compiler uses gcc4.7.2-5. I used the sources for gcc-4.8.2 and binutils-2.24 to generate the cross compiler.

Answer 1

/opt/cross/bin/mipsel-unknown-linux-gnu-gcc -mips1 hi.c

Add a SYSROOT to the compile command. It should look similar to:

/opt/cross/bin/mipsel-unknown-linux-gnu-gcc -mips1 --sysroot=/opt/cross/... hi.c

The SYSROOT will provide the header and library path automatically (rather than adding -I and -L individually).

You will know when you have a SYSROOT because there will be a bin/, include/ and lib/ in the path used. For example, here's a SYSROOT for arm-linux-gnueabi (i.e., arm-linux-gnueabi-gcc and arm-linux-gnueabi-g++):

$ ls /usr/arm-linux-gnueabi
bin  include  lib

So, in this example, you would use --sysroot=/usr/arm-linux-gnueabi.

If you need help with locating a SYSROOT, then perform a find:

$ find /usr -name crt1.o
/usr/arm-linux-gnueabi/lib/crt1.o
/usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o
/usr/lib/x86_64-linux-gnu/crt1.o

In your case, you would probably search from /opt/cross. Obviously, you would want the one for the target (arm-linux-gnueabi), and not the ones for the host (x86_64-linux-gnu).

Answer 2

Adding --sysroot= would resolve this issue. As you are cross-compiling you shouldn't select just any other folder which has crt1.o or crtX.o as your sysroot directory. It could be your host-machine's files. (Which if you are running on a x86, it would be for x86). Again it varies from 32bit and 64bit.

With newer version's of GCC toolchain, you need to have a sdk part of it which has the appropriate sysroot and crt1.o. This should go with your ABI and your target architecture.