How do you cross compile ELF executables for Android?

Question

I have prepared a sample C code below to make it run on Android Operating System by following these procedures,

/*test.c file*/
#include <stdio.h>

int
main(int argc, char **argv)
{
    printf("Android Test Application.\n");
    return 0;
}

$ arm-none-linux-gnueabi-gcc -o test test.c -Wall

I copied the binary file --test-- into target device "/system/bin" directory.

When I attempt to make cross-compiled binary run on the target system, I am getting this error

$ pwd

/system/bin

$ ./test

bash: ./test: No such file or directory

$ ls -al | grep test

-rwxr-xr-x 1 0 0 8384 2011-12-22 15:26 test

although the binary file --test-- is already in "/system/bin" directory.

My cross-compiler is

$ arm-none-linux-gnueabi-gcc --version

arm-none-linux-gnueabi-gcc (Sourcery G++ Lite 2009q1-203) 4.3.3 Copyright (C) 2008 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Why I am getting this error?

bash: ./test: No such file or directory

Solution

This problem was related to the dynamic loader. When I checked the output of the binary file with readelf, I notified that the cross-compiler that I use has a different type of default dynamic loader - "/lib/ld-linux.so.3", but Android uses "/system/bin/linker"

$ readelf --program-headers test

Elf file type is EXEC (Executable file)
Entry point 0x8380
There are 8 program headers, starting at offset 52
    Program Headers:
Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
EXIDX          0x0004fc 0x000084fc 0x000084fc 0x00050 0x00050 R   0x4
PHDR           0x000034 0x00008034 0x00008034 0x00100 0x00100 R E 0x4
INTERP         0x000134 0x00008134 0x00008134 0x00013 0x00013 R   0x1
       [Requesting program interpreter: /lib/ld-linux.so.3]
LOAD           0x000000 0x00008000 0x00008000 0x00550 0x00550 R E 0x8000
LOAD           0x000550 0x00010550 0x00010550 0x00124 0x00128 RW  0x8000
DYNAMIC        0x00055c 0x0001055c 0x0001055c 0x000f0 0x000f0 RW  0x4
NOTE           0x000148 0x00008148 0x00008148 0x00020 0x00020 R   0x4
GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RW  0x4

In order to change dynamic loader(dynamic linker), "--dynamic-linker=/path/to/loader" should be used for the linker.

$ arm-none-linux-gnueabi-gcc -o test test.c -Wall -Wl,--dynamic-linker=/system/bin/linker

Comments

[Santiago Villafuerte]

This is very useful to compile binaries for the recovery file system in Android where no /system/bin/linker is available and the path has to be redefined. Thanks.