UDS from an embedded hacker’s perspective

“The Summit covered a wide range of topics from low level kernel
details, to best community practices, but the ARM netbook support
sessions were particularly interesting. At this UDS, the Ubuntu ARM
developers set out to enable support for many ARM machines in a
single distribution, a difficult task due to the lack of a standard
firmware interface on ARM systems; a familiar problem to embedded
developers. This report covers the solutions debated at UDS —
including Kexec bootloaders and the flattened device tree —
and the choices made for the next Ubuntu release.

“Ubuntu has supported the ARM architecture since the 2008
Intrepid Ibex (8.10) release, but the relative lack of consumer
hardware has effectively made it interesting only to developers.
During the Lucid cycle we can expect that to change as Canonical is
working with ARM netbook OEMs to provide full support for the new
devices that are widely anticipated to appear on the market in the
new year.

“However, support for a wide range of ARM devices is complicated
by the absence of any form of a firmware interface standard for ARM
systems. The vast majority of ARM designs are embedded systems with
no expectation that the end user will install their own software.
General purpose ARM computers are historical rarities; the notable
exceptions being the original Archimedes, and the Corel Netwinder.
As such, unlike the x86 architecture where an IBM PC-type BIOS is
mostly a given, device manufactures can (and do!) implement
whatever firmware interface best meets their needs. Every device
has a different method for booting the OS. Additionally, since
firmware provides little if any information about the hardware, the
kernel must be hard coded with device addresses and configuration
information.”

Complete Story