Cross-compilation

Many or even most tasks can be implemented using the integrated SDK with the C-like scripting language and the router API functions.

However, if for some reasons you want or have to cross-compile a C application, you will find a cross-compilation toolchain on our FTP server. This toolchain consists of a compiler ( GNU Compiler Collection (GCC) version 4.4.5), a assembler and linker ( GNU binutils) and a C standard library ( uClibc version 0.9.31), all built to produce binaries for NetModule Routers with Freescale/Motorola PowerPC (MPC830x) CPUs, namely NB1600, NB2700, NB2710, NB3700, and NB3710.

For further introduction to GCC please refer to An Introduction to GCC, chapter 2 and following ones.

1. Download and install the toolchain on your Linux x86 PC

wget ftp://share.netmodule.com/router/public/toolchain/toolchain-ppc-4.4.5-x86_64.tar.bz2
tar -xvf toolchain-ppc-4.4.5-x86_64.tar.bz2 -C /opt
export PATH=$PATH:/opt/toolchain-ppc-4.4.5-x86_64/bin

2. Write a program

hello.c

#include<stdio.h>
#include<features.h>
int main()
{
    printf("Hello World\n");
    #ifdef __UCLIBC__
    printf("We are coding against uClibc\n");
    printf("uClibc v%i %i.%i\n",__UCLIBC_MAJOR__, __UCLIBC_MINOR__, __UCLIBC_SUBLEVEL__);
    #endif
    return 0;
}

The Linux man-pages project documents the Linux kernel and C library interfaces that are employed by user-space programs. Section 2 documents the system calls provided by the Linux kernel and section 3 documents the functions provided by the standard C library. Another reference guide for the C standard library can be found here.

3. Compile it

powerpc-openwrt-linux-gcc -Wall hello.c -o hello

4. Copy it to the router (e.g. via SCP) and run it.

For small projects or if you don't have a Linux environement you can also use the very small Virtual Box Image. The image uses Tiny Core Linux (http://tinycorelinux.net/). Please read the starup message carefully.

This example shows you how to compile a program from source. The program in this example is jq

wget https://github.com/stedolan/jq/releases/download/jq-1.5/jq-1.5.tar.gz
tar -xzf jq-1.5.tar.gz
cd jq-1.5
CC=powerpc-openwrt-linux-gcc ./configure --host=powerpc --disable-maintainer-mode
make

We can now check the file type and we see, that the program has been compiled for PowerPC

file jq
jq: ELF 32-bit MSB executable, PowerPC or cisco 4500, version 1 (SYSV), dynamically linked (uses shared libs), with unknown capability 0x41000000 = 0x13676e75, with unknown capability 0x10000 = 0xb0402, not stripped