Reducing OS Boot Times for In-Car Computer Applications

A modern high-end car now comes equipped with a half dozen computers
outside of the ones that run the engine. Vehicles now come with XM or
Sirius radio, OnStar GPS and concierge, Network Car telemetry functions
and built-in navigation systems from a number of vendors. The tops of vehicles
now are adorned with sharkfin-shaped antennas for satellite audio, GPS and
cellular networks. Although telemetry is the catch-all word for the new
automobile-computer market, many in-car computer applications have
little to do with remote measurement. Cars now may contain info-tainment
related computers and MP3 players, such as the Phatnoise Audiokeg, and
even may download those MP3s over Wi-Fi with Rockford Fosgate's Omnifi.
And, let us not forget iPod and its mobile brethren, all of which spend
much of their lives in the center console of a car, wired to its power and audio.
General Purpose Computers
The problem with these computer-driven devices is, although they do
one thing well, they aren't expandable and reprogrammable. Yet, besides
the applications noted above, many people probably would wonder why they
really need a general purpose computer in their cars. In many ways, the new
devices for cars simply extend existing application models. For
instance, XM and Sirius are more radio stations, and AudioKeg,
Omnifi and MP3 players in general are large CD changers,
which simply are much larger boxes of tapes.

The strength of a general purpose computer is it allows applications
that haven't even been thought of yet to appear. In the early 1980s,
people were receiving strong marketing messages that they needed a
personal computer in their homes, but many didn't know why. To organize
recipes? To keep a checkbook? But the emergence of killer applications
continued until almost every household had a computer.

Killer application sounds like a very bad thing to use while
driving a car, but the fact remains that many new applications no one
has thought of yet will be possible to use with a general purpose platform. A
single purpose Wi-Fi enabled audio jukebox can download MP3s and audio
books--but can it get your e-mail and read it to you while you're on the road? Can it
download all your blogs and read those to you? Can it share audio with
other drivers on the road? Can it keep a full GPS log of your travels
and allow you to annotate them as you go? Can it wake up and record your
favorite public radio show over the weekend and have the other morning
show ready for you on your commute home, à lá TiVo for radio? All these
applications and more become possible with an open programmable platform.

Car stereos have been running Linux for years. The question now is how to get
such a general-purpose platform into the mainstream and get developers
working on new applications for it.
Engineering Challenges of an In-Car PC
Although we've discussed our motivation for wanting general purpose
computers in cars, it should be obvious that existing computers are unsuitable for the
task. The major engineering challenges for getting existing computers
into the car are heat, power, vibration and boot times.

Many of the above problems have been solved by some innovative vendors who
have been working on these problems for the consumer and do-it-yourself
system builder market. The embedded systems industry has been
making shakable, bakeable, low-power, fast booting devices for years,
but a popular mini-ITX form factor has been developed and adopted by a
number of systems manufacturers, notably VIA Technologies, with their
cheap, feature-packed, small and x86-compatible motherboards. These
low power boards have CPUs that can run passively cooled (fanless) and
boards designed for high heat environments. This, combined with the
direct DC to DC power converters that provide ATX-like power directly
from 12V batteries, have helped a large and growing community of car PC
hobbyists get PCs into their cars. Laptop drives, rubber shock-mounting
and ruggedized cases have all but solved the vibration problems. But
with standard PC BIOSes doing everything from hard drive autodetection
to plug and play, and then standard OSes taking from 30 seconds to a
minute to start up, boot time remains a barrier for a car-ready computer.
Boot Time Reduction
Cold-booting the OS is one of the few options available to a car
PC. Although many low power modes exist for desktops, these can draw as
much as 100mA of current for such features as USB and Wake-on-LAN.
Although this may be negligible for a computer plugged into the wall, in a car this
is the battery-draining equivalent of leaving the dome light on. Thus,
a full power down is necessary. Also, many of the shutdown circuits
used in conjunction with car PCs completely cut power to the PC,
sometimes quite abruptly, making even hibernation (the saving of
the system state to disk) out of the question.

Waiting 30-60 seconds for a PC to boot once you get in your car is
annoying and keeps car PCs out of the mainstream. When auto manufacturers
specify in-car systems such as navigation, they usually insist on very,
very rapid boot times, such as 100 milliseconds until the splash screen
appears or 300 milliseconds until the system is usable.

The late John Muir took a philosophical approach to waiting for slow
starts in his 1969 book How to Keep Your Volkswagen
Alive, where he recommended rolling a cigarette and getting a good toke going,
by which time the car will be warmed up and ready to drive. However, as
smoking anything but cannabis has been all but outlawed (in California
at least), the only solution that remains for car PCs is to reduce
boot times.
Reducing OS Boot Times
Some basic approaches to reducing boot time are:

• Speed up the computer until the slow old OS seems to boot quickly. This
  includes speeding up hardware and memory or replacing mechanical disks
  with solid state Flash memory.
• Shrink the boot image by removing features so
  it boots faster.
• Use an OS that simply loads another program,
  such as DOS, and put the hardware drivers in the program itself.
• Parallelize the boot tasks, sort of booting everything at once, so
  all the different drivers and tasks can do their several seconds of
  waiting at the same time.
• Boot in stages so the system appears to have booted because it
  starts doing something that distracts the user, and then finish
  booting.
• Save a canned memory and system state to disk, so that booting can
  occur as fast as the memory image can be read from disk
  (hibernation).
• Put parts of software in hardware or firmware, such as replacing the
  BIOS itself with the OS.
• Somehow, never shut down or crash. Run on a microcontroller that takes
  less than a milliamp of current so you can run off a battery for
  years.

In subsequent articles, we will be focusing on how to get an
operating system to appear to boot instantaneously. We will be basing
our analysis on the VIA EPIA-M and EPIA-MII boards, the ones we are using
in our in-car computer systems, and discussing the various application
needs we are trying to satisfy. We will enumerate some test applications (TiVo
for radio), go through the above list and select several boot
reduction approaches to try, eliminating those approaches that are
unfeasable and/or too expensive. Finally, we will produce a list of all the boot time reducing
solutions we have found and report on the boot times we've achieved
on our hardware.

Damien Stolarz is an, inventor, writer and engineer with years of
experience making different kinds of computers talk to one another. He is
the CEO of Carbot, Inc., an in-car computer company, and Robotarmy
Corp., a networking software development house.