Time to set a checkpoint on the USB image...
The Ubuntu Mobile and Embedded (UME) edition is being developed taking into account the current and next generation of low-power processor and chipset architectures. However, all the tools and design features are made immediately available for the generic Ubuntu distro, making it suitable for a generic i386 architecture as well.
When I started playing with UME I thought that a set-top box like appliance has many similarities to a portable device, i.e. it must boot fast, support any power cuts gracefully, provide a sort of controlled environment where modifications to the core system are arbitrated, etc.
So I started using the UME SDK (a.k.a. PDK, Platform Development Kit) and managed to create an i386 platform for a generic PC (see
https://wiki.ubuntu.com/CreatingAGeneric...formForMIC).
With these small (!!!) bits in place the PDK is able to produce read-only and R/W LiveUSB images, as well as an install USB image for an internal hard disk installation.
The current test image has support for Intel GPUs only, has a fresh build of XBMC-linux running as the X11 "shell" full screen (no window manager), mounts USB flash disks automatically and has ssh and ftp servers running at boot - DHCP server needed. All xorg drivers included in the standard ubuntu distro are already included, but a custom xorg.conf is needed to enable them.
Everything included is around 300 MB, where 100 MB is XBMC only... Size can be trimmed by removing lots of stuff (unused xorg drivers as an example), but it's not a priority right now.
The image is currently not available in the public since we are still looking for a suitable hosting solution, but hopefully an announcement will be possible in a short time. However, take into account that this is a PROOF-OF-CONCEPT only, it won't be supported by the core developers and myself
Besides, there are areas needing improvements, such as faster boot time: right now it's similar to a full Ubuntu system, i.e. around 30 seconds from power switch to XBMC running full screen on a low-end C2D.
Anyway, stay tuned for more developments and feel free to comment and provide any feedback/ideas.
Cheers
Luigi