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German Palmtop Pro Article - English translation
Page last updated 25/7/99
 Psion
as a Server? Linux on a Series 5
Many may think, "now, those guys have completely cracked,"
when they hear
of the Linux 7k project. A series of developers
have set out to port the
public domain Unix operating system, Linux, to the Psion
Series 5. In the
mean time, the first bootable kernel can be retrieved
off the internet,
though, admittedly it is not yet much more than a proof
of concept.
Still, Linux on the Psion already offers enough "food
for thought"
for both the Psion user interested in Linux, as well
as the Linux user
looking for a mobile platform for his Unix desktop.
The Linux 7k project has taken up porting Linux to the
CL-PS7100
processor, which is built into the Series 5. The
project's home page
(www.calcaria.net) reads that the computing power of
the Psion 5
corresponds roughly to the Intel 486/33; moreover, 8-MB
RAM provides
plenty of working memory and, with Flash cards, expandable
"disk space".
Technically, there are no insurmountable barriers, especially
when one
considers that Linux has already been running on the
ARM processor on
which the Psion 5's CPU is based.
Besides the technical feasibility is naturally the question,
"why?"
What do I do, as a Psion user, with a server operating
system? The well
known Psion software developer, Mark Esposito, has his
opinion: "I can't
imagine any market need for a server on a PalmPro.
On the contrary,
the Psion is actually destined to become a client to
a Linux server.
Still, I am sure that some Psion maniac will host a web
server on a
Series 5 just for fun. But that machine will then
no longer be portable!"
On the other hand, Mark also sees a positive aspect: "Surely,
the Linux
project can be useful sometime, for example when perhaps
one day a larger
EPOC machine is introduced." This hope is certainly
not unjustified,
indeed this does not depend on the EPOC operating system,
since it will
be replaced by Linux. Decisive for the ability
to run is the hardware.
Naturally, there exists for Linux in the the PC-version
an almost
boundless variety of application programs from Freeware
gimmicks all the
way up to complete (and for personal use, free) office
suites such as
the German-made StarOffice. Disregarding command
line programs, that
are mostly interesting to hackers, most programs run
with a graphical
interface, namely under X windows, the graphical front
end for Linux--one
can see the analog between Linux and X windows and the
PC configuration
of DOS and Windows. X windows, however, needs memory
and performance
that is on the edge of what the Psion allows.
All applications must be recompiled for use on the Psion,
in many cases
the source code will probably need to be adapted.
The biggest difficulty
will certainly lie with the differences between desktop
computer hardware
that is in many cases divergent, and the services of
the Palmtop.
For one thing, the Psion display is a completely different
format than a
desktop monitor. Likewise, Linux applications use
relatively large areas
of the screen as opposed to Psion programs--it is not
without reason that
the Psion menus close when they are not being used.
Admittedly, window
managers such as fvwm or KDE allow the look of the X
windows desktop
and the single window to be extensively adapted.
This could be one
possibility for technical realization: the graphical
engine of X windows
allows for nearly unlimited configuration such that,
with a graphics
driver and an appropriate entry in the Xconfig configuration
file, the
"wide screen" display of the S5 should be made usable.
A special Psion
window manager could make available the hide-away menus
and windows
without headers, so that, in the end, one still winds
up with the Psion
look and feel. X windows possesses, by the way,
usually several virtual
desktops that would create space on the limited display
of the Psion.
Keep in mind that it appears that quite a bit of work
needs to be put into
the Linux program for it to become an EPOC replacement.
There by comes
one again on the question of purpose, since the Psion
brings with it very
mature EPOC applications, likewise such applications
are available from
third-party vendors. "What then can Linux do that
EPOC cannot--and what
could be so useful on a Palmtop?" In a word, nothing
at the moment; this
certainly could change in the future, and if such complex
applications
as StarOffice would run on the Psion Linux, this would
naturally mean
a quantum leap--directly compared to Windows CE--in functionality.
In complete reverse, at least in the view of the Linux
user, the
proof of concept is the most interesting thing.
One of the Linux 7k
developers says, "All in all, I believe that there is
interest within
the Linux community in a very portable Linux platform
that doesn't use
up batteries excessively. On my desktop I use Linux
and public domain
software. Why then shouldn't my PDA also run Linux
with free software?"
So, a portable Linux computer on which the same applications
run as are
on the desktop--compatible data formats, unified operation?
Surely, a captivating thought, but this is reminiscent
of the story
of Windows CE: At some point the developers must realize
that it is
pointless to store the "space wasting" PC data formats
on the Palmtop, and
begin to pare down the format--which is binary compatible
with the data.
Naturally, the Psion Series 5 offers with its capabilities--expandable
up
to 40-MBytes of flash RAM--significantly more storage
than the Series 3,
for example, which is fundamentally why it is possible
to store the Linux
formats, but this is reminiscent indeed of trying to
make a moving van
out of a sports car.
Naturally, it is simpler to network two Linux computers
than to connect
an EPOC computer to a Unix desktop. Using TCP/IP,
or rather PPP, a true
network connection must be created between the PC and
the Psion--data
exchange via FTP or through mounting the Psion disks
into the PC
filesystem are in the technical realm.
Is this all garbage? Certainly not, since the possibility
of putting
Linux in the hip pocket has its advantages, and as Mark
Esposito says,
"Who knows what EPOC machine the future will bring?"
As proof that
the Psion Series 5 is a real computer in pocket format,
the Linux 7k
demonstrates once and for all. Moreover, for the
Unix service technician
it can serve, for example, as a portable display for
man pages in Unix.
Further uses probably will pop up faster than can be
anticipated.
In closing, the developers of the Linux 7k project are
to be wished much
luck and success.
Linux 7k--technical
The main problem for booting a Linux system on the Psion
is that the
operating system is not on hard disk as it is on the
PC. Rather it is,
so to say, hardwired in ROM. Inevitably, after
a reset, the Psion first
boots EPOC. For the way to solve this, however,
there is already an
example: there exists for the PC a program called loadlin
with which
Linux can be booted from within DOS. During the
boot process loadlin
loads itself into main memory and "formats" it so that
DOS is properly
disabled. The Linux kernel then boots into the
now free main memory.
This process is certainly not new: such powerful operating
systems
as Novell Netware are also booted into from DOS, actually
DOS is not
"shut out" of memory, rather it "sleeps" in the background
until it is
explicitly removed from memory.
The process to start Linux on the Psion is similar, except
the
implementation is more difficult since EPOC is, according
to the Linux
7k specialists' information, "more sophisticated" than
DOS. (Even I
knew that!) An ARM assembly program called ARLO
(Advanced Risc Loader)
is run under EPOC which loads the Linux kernel.
Currently, only a few
of the commands work--as mentioned, the kernel is in
a state of "proof
of concept". A listing of the C: "drive" is possible,
and a list of
process can be called up on the screen. New recently,
a CompactFlash
card can be addressed, also. The next step is full
support of the cards
in order to create a bootable flash card. With
that the largest problem
of the current state of development would be solved:
running the Linux
kernel crashed the Psion which must then be brought back
to life with
a hard reset.
The current state of development does not appear too sensational.
One must understand, however, how much preparation was
needed in order
to be able to just boot the kernel. A "cross platform"
development
environment had to be created, by which means Psion-Linux
programs
could be generated on a Linux PC. Due to the restrictive
information
policies at Psion, it was also a bit of work to get basic
information
about the hardware. The experience demonstrates,
however, that the Linux
development, after the first difficulties on a new hardware
platform
are solved, is picking up at a furious pace. From
the Linux 7k project
certainly more is to be expected! Further information
can be found at
http://www.calcaria.net/index.html.
------------------------
Translated by Paul Woods
paulw@@cv.hp.com
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