HOWTO_embedded

Why embedded gentoo

Router like(small storage space)

• Linux can run on a wide variety of devices, including PDA's and routers

In the case of router-like devices(those with limited storage space, but not PDA's), the manufacturer will ship the device with firmware (sometimes linux -based, sometimes not) which may lack needed features. In response, the community may develop their own firmware based on linux, but these releases often are not a precise match for a user's requirements.

So, if a user desires a set of features that are not covered by any one firmware release, what options are available to him?

• Customising an existing firmware release
• Building your own firmware with LFS
• Building your own firmware with Gentoo

The first 2 options can be very difficult, requiring considerable skill and time, while (comparatively) the Gentoo option is much more simple.

Pda

Normally a PDA that has already linux running can run familiar (or it's in developement), but that system is debian based and unfamiliar to a Gentoo user.

Other stuff

Some people port linux to new devices for fun and make an 'official' distribution for it and so there is only one distribution and you have the same choices than with the routers in order to add functionality:

• Customising an existing firmware release
• Building your own firmware with LFS
• Building your own firmware with Gentoo

Why is customising firmware or using LFS is so difficult

Customising

Developing a distribution such as knoppix,debian is difficult. It's much more involved than just making ./configure , make , make install etc because sometimes it works and sometimes not, and when it doesn't work you are lost and need to figure out why it doesn't compile.

Gentoo avoids the majority of these problems with Portage.

LFS

The same issues apply to LFS, with the additional problem of not having a base system, so you will need to learn a lot of interesting things (read as considerable investment in time and effort) and do everything manually...resolve dependencies, make init scripts etc.

Gentoo has a lot of tools for this (portage,rc scripts,configuration update uttilities...)

Other Gentoo Advantages

Gentoo has the following advantages for embedded systems:

• Source based
• Modular distribution
• Some tools that render the developer's life easier

What needs to be done:

• Use a working linux distribution and get the patch and all the stuff in order to get Gentoo working on the device
  • Get the patches and kernels
  • Make some different ebuilds (integrate patchs) or updates the main ones in order to be compatible with the devices
  • Make a new profile
• Adapt gentoo to a resonable size in case of limited storage space