Compiling simple C program does not link properly

Question

I'm trying to compile a simple C program, but apparently the program is not linking properly.

hello.c

/* Simple C program. */
#include<stdio.h>

int main() {
printf("Hello MIPS! \n");

return 0;
}

I am trying to compile the program with the following command, mips-gcc -v hello.c -o hello

The output I'm getting when I try to compile / link the program,

Using built-in specs.
COLLECT_GCC=bin/mips-gcc
COLLECT_LTO_WRAPPER=/opt/cross/gcc-mips/libexec/gcc/mips/4.8.2/lto-wrapper
Target: mips
Configured with: ../gcc-4.8.2/configure --target=mips --prefix=/opt/cross/gcc-mips --enable-interwork --enable-multilib --enable-languages=c --with-newlib --with-headers=/opt/cross/src/newlib-2.1.0/newlib/libc/include/ --disable-libssp --disable-nls
Thread model: single
gcc version 4.8.2 (GCC) 
COLLECT_GCC_OPTIONS='-v' '-o' 'hello'
 /opt/cross/gcc-mips/libexec/gcc/mips/4.8.2/cc1 -quiet -v hello.c -quiet -dumpbase hello.c -auxbase hello -version -o /var/folders/1z/k_by6wd95tsccc6s1_tkttpr0000gn/T//ccqPwmTq.s
GNU C (GCC) version 4.8.2 (mips)
    compiled by GNU C version 4.2.1 Compatible Apple LLVM 5.1 (clang-503.0.38), GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
#include "..." search starts here:
#include <...> search starts here:
 /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/include
 /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/include-fixed
 /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/../../../../mips/sys-include
 /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/../../../../mips/include
End of search list.
GNU C (GCC) version 4.8.2 (mips)
    compiled by GNU C version 4.2.1 Compatible Apple LLVM 5.1 (clang-503.0.38), GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: e28a4def2fba399e5af333f18f473404
COLLECT_GCC_OPTIONS='-v' '-o' 'hello'
 /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/../../../../mips/bin/as -EB -O1 -no-mdebug -mabi=32 -o /var/folders/1z/k_by6wd95tsccc6s1_tkttpr0000gn/T//ccgd49A6.o /var/folders/1z/k_by6wd95tsccc6s1_tkttpr0000gn/T//ccqPwmTq.s
COMPILER_PATH=/opt/cross/gcc-mips/libexec/gcc/mips/4.8.2/:/opt/cross/gcc-mips/libexec/gcc/mips/4.8.2/:/opt/cross/gcc-mips/libexec/gcc/mips/:/opt/cross/gcc-mips/lib/gcc/mips/4.8.2/:/opt/cross/gcc-mips/lib/gcc/mips/:/opt/cross/gcc-mips/lib/gcc/mips/4.8.2/../../../../mips/bin/
LIBRARY_PATH=/opt/cross/gcc-mips/lib/gcc/mips/4.8.2/:/opt/cross/gcc-mips/lib/gcc/mips/4.8.2/../../../../mips/lib/
COLLECT_GCC_OPTIONS='-v' '-o' 'hello'
 /opt/cross/gcc-mips/libexec/gcc/mips/4.8.2/collect2 -EB -o hello /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/crti.o /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/crtbegin.o -L/opt/cross/gcc-mips/lib/gcc/mips/4.8.2 -L/opt/cross/gcc-mips/lib/gcc/mips/4.8.2/../../../../mips/lib /var/folders/1z/k_by6wd95tsccc6s1_tkttpr0000gn/T//ccgd49A6.o -lgcc -lgcc /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/crtend.o /opt/cross/gcc-mips/lib/gcc/mips/4.8.2/crtn.o
/opt/cross/gcc-mips/lib/gcc/mips/4.8.2/../../../../mips/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000000400038
/var/folders/1z/k_by6wd95tsccc6s1_tkttpr0000gn/T//ccgd49A6.o: In function `main':
(.text+0x18): undefined reference to `puts'
collect2: error: ld returned 1 exit status

Answer 1

Stop passing -v ; it just produces a crazy amount of debug output that doesn't relate to your problem.

mips-gcc -o hello hello.c produces something like

ld: warning: cannot find entry symbol _start; defaulting to 0000000000400038
ccgd49A6.o: In function `main': (.text+0x18): undefined reference to `puts'

The second error indicates that you need -lc on the end of your command line to pull in the libc library (which provides puts ). The first error indicates that you also need a crt0.o from somewhere (to provide _start ). In other words, you're invoking the compiler in some kind of "bare-metal" mode, where it assumes you're writing code to run directly on the machine instead of in a hosted C environment (where you'd have access to command-line arguments, and a standard library, and a filesystem, and so on).

Your problem seems similar to this guy's in 2006: http://osdir.com/ml/lib.newlib/2006-07/msg00029.html The solution there was to use -T nullmon.ld to specify a linker directive file that included crt0.o ; and also perhaps to use mips-elf-gcc instead of mips-gcc .

However, programming for bare metal usually requires that you start very low-level and not try anything as complicated as C until you've already gotten familiar with assembly. See the answers to Bare metal cross compilers input for more information (and it even talks specifically about MIPS!).