如何为微处理器SA1100安装交叉编译器（在ubuntu 12.04 LTS上）？

Can someone please tell me how to install the cross compiler (programming language C) for the SA1100 microprocessor? I have ubuntu 12.04 LTS. I´m a complete noob to Linux, I just installed Ubuntu yesterday. I need a special variant of the GCC compiler that is named "arm-unknown-linux-gnu-gcc" but don know how to do it.Can someone please tell me how to install the c