If the target has sufficient IO devices (eg screen and keyboard) then it can be used without a host. However, during initial development a host is normally used as a console (screen and keyboard), for compiling new code and for monitoring debug output.
There are several reasons why this is practical:
you will probably keep rebooting the target;
it will probably crash a lot if you are doing any low-level development, or the hardware's not quite debugged yet;
there may well not be space for the toolchain software on the target;
you will normally be more familiar with the host environment.
As the host is usually an x86 PC rather than another ARM-based machine this means that you will need to cross-compile software to run on the target processor. You can arrange to use an ARM machine as the host (eg an Acorn Risc PC, Netwinder, CATS board) but even here you usually need to separate the host and target environments as they will probably be using different kernel versions and perhaps library versions.
You can have either a GNU/Linux or a Windows box as the host. As you are working with Linux on the target it is useful in many ways to also have a Linux host - the toolchain is easier to set up, you can easily mount and try out your RAMdisks etc. Much of this book assumes that you have access to a GNU/Linux host. However we recognise that many developers wil have a Windows box on their desks and may not wish or be able to change just yet. The best solution is to the use the Cygnus unix-like environment for Windows which gives you the functionality you need. A chapter for this book, describing the necessary software and techniques, is in preparation for the next edition. In the meantime either use your skill and judgement, or get a GNU/Linux box too.
Getting a cross-compiler toolchain set up used to be very difficult, requiring much gurudom and attention to a host of details but with the precompiled toolchains on this CD it is very easy. Chapter 8 gives details of both the ready built toolchains you can install, and explains how to build a new one should you need something different from that which is provided.
