 | Level: Introductory Peter Seebach (dw@seebs.net), Writer, Freelance
22 Nov 2006 The Linux®-based Nokia 770 Internet tablet is an intriguing
gadget for Linux enthusiasts. Though it lacks most of the personal information
manager (PIM) apps one would expect from a palmtop-sized device, recent advances in
its development environment make it a toybox for hobbyists and professional embedded
developers alike.
The Nokia 770 was released to some fanfare in the Linux world. Unlike the Zaurus
before it, or Pocket PC or Palm systems, the 770 does not offer personal
information manager (PIM) functionality; indeed, it does not provide particularly
easy access to the features that would be needed to make a PDA. Instead, it's
pitched as an "Internet tablet," providing applications such as a Web browser and
an e-mail client.
Nokia recently released an update to the 770's software that makes it a little
more friendly to users who want to poke around on the device. In earlier releases,
it was necessary to enter research and development (R&D) mode to obtain
root access. Version 1.05 makes it possible to work around that more easily.
The Nokia 770 has two storage devices available, an internal flash device
(formatted as JFFS2), and a plug-in card (formatted as a FAT filesystem). The
770's connectivity options are interesting. The device's default behavior when
connected over USB is to serve as a mass storage device. The 770's internal
storage is not exposed this way; instead, the plug-in card is made available to
the upstream computer as a generic USB storage device to allow easy transfer of
files. While the 770 is connected over USB this way, the card is unmounted from
the 770, to prevent corruption. This is an elegant answer to the question of how
to present access to the device's files.
For the most part, the device doesn't require a lot of manual configuration; it
can connect to Bluetooth phones or Wi-Fi networks, either automatically or with
minimal instruction. The progress that Linux-based systems have made in automatic
network configuration is striking.
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About that USB keyboard support
The Nokia 770's USB keyboard support is absolutely fascinating, because it's
primarily a hardware hack. The problem is essentially physical; the 770's USB
hardware has a plug of the sort usually used for downstream devices, and the
chip it's connected to wakes up only if 5 volts of power is provided to it --
the way it would be if the device were used as a downstream machine. There is
also a software problem: the machine must be configured in USB host mode, rather
than USB device mode. This requires a bit of messing about with the flasher
utility. Oddly, although the Nokia pages are mostly built in terms of
Windows® downloads, the flasher utility is available for Mac OS X and
Linux only.
But, since I'm a software guy, the part I find fascinating is the development
of circuits that add 5 volts of power to a USB cable. There's a link to
information about this in the Resources section,
below.
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An overview of the installation
The 770's installation, as is often the case for such devices, is built around
BusyBox. The startup scripts are fairly standard Debian scripts, complete with
README files. The interesting part is the user interface and development tools,
which are a noticeable improvement over the relatively primitive environment of
the Zaurus. The developer support, provided through the maemo.org pages, is fairly
comprehensive. (See Resources for a link.)
And this is where the 770 departs from the previous Linux-based devices I've
looked at: the developer support seems more active, and more involved. The 770
doesn't do all that many things very well out of the box (with Web browsing being
a pleasant exception). However, Nokia seems to be looking at the potential for
community development as a major benefit of the machine. The developer tools are
being pitched towards hobbyists, not just commercial developers. The utility used
to load new ROM images and set special device flags (such as the R&D mode)
is available for download.
This has resulted in a fair amount of interesting development. For instance, like
most tablet or PDA devices, the 770 has a significant weakness in the area of text
input: even if you like the keyboard or handwriting recognition, it still chews up
screen real estate, which is not cheap to come by on a device with a four-inch
screen. Now, hobbyists have made Bluetooth and USB keyboards work with the device;
life is good. (See the sidebar for more information.)
Getting access
In earlier releases of the 770, it was necessary to use the flasher utility to
put the device into R&D mode, then run the
gainroot script. The script itself, illustrated in
Listing 1, is kind of interesting.
Listing 1. The gainroot script
#!/bin/sh -e
trap exit SIGHUP SIGINT SIGTERM
PATH=/bin:/usr/bin:/sbin:/usr/sbin
MODE=`/usr/sbin/chroot /mnt/initfs cal-tool --get-rd-mode`
if [ x$MODE = xenabled ]
then
echo "Root shell enabled"
/bin/sh
else
echo "Enable RD mode if you want to break your device"
fi
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The default sudoers file permits anyone to run this script via sudo; if your 770
is in R&D mode, you get a shell; otherwise, you get the humorous warning
message.
In the more recent release, a slightly simpler option is available: you can ssh
in as root. This requires you to download a third-party dropbear package, but then
you just ssh in as root, with the password rootme. The widely documented
default password and permitted root login make that password fairly descriptive;
if you install the ssh server, change your root password. No, really. Do.
One obvious solution would be to set the user password, configure /etc/sudoers,
then run passwd -l root to disable root logins
entirely.
The point of this digression is to establish that, while some vendors are
providing minimalist subsets of Linux, carefully crippled and protected, Nokia is
barely stopping short of waving a compiler in your face. This device is, at the
moment, not a mass-market consumer item for most people; it's a toybox. There's
something really nice about finding a fairly full-featured Linux on a tiny little
device.
Desktop cruft
The install on the 770 has never quite decided whether it's an embedded system or
a full-fledged desktop Linux. Earlier releases provided a system image in which
the installed files were not controlled by the package management system; in the
release I looked at, the package manager comes with over 900 packages, some more
optional than others, as shown in Listing 2.
Listing 2. The beginning of a very long list
# dpkg -l
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Installed/Config-files/Unpacked/Failed-config/Half-installed
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name Version Description
+++-==============-==============-============================================
ii adduser 3.51 Add and remove users and groups
ii apt 0.6.42.3osso13 Advanced front-end for dpkg
ii archtunjo 0.0.8-4 the D-BUS wrapper for games
ii autoipd 0.9.6-1osso9 Autoipd from Howl
ii base-files 3.1.osso2 Debian base system miscellaneous files
ii base-passwd 3.5.7.osso1 Debian base system master password and group
ii bluez-utils 2.25-cvs200605 Bluetooth tools and daemons
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This sets the stage for a more flexible install, in the event that you would want
to make room to install additional files -- not that the system is likely to run
out of room quickly. The bulky files that generally fill portable gizmos are
likely to live on the removable card rather than in main storage, anyway.
Presumably, a bit of work could have stripped out a few programs or scripts that
aren't doing much; for instance, the glibc.sh script that warns about glibc
compatibility requirements on AMD64 systems is, unsurprisingly, totally unused.
(It does actually have some marginal reference to ARM systems; they need kernel
version 2.4 or later. The 2.6.16 kernel in the release I examined is probably
fine.) Still, every system I've looked at has some stuff like this; in practice,
it's probably not worth the hassle of trying to track it down to remove it.
Development
The software development environment for the 770 is something new, although an
end user of the 770 wouldn't see this, as the development tools are not actually
loaded on the device but rather run on a workstation or PC. About three years ago,
I wrote about cross-compilation for the Sharp Zaurus (see Resources for a link). The process was fairly involved. The 770 uses a new
cross-compilation setup called Scratchbox, development of which was
sponsored by Nokia. This is a substantial improvement, providing an environment in
which target-system binaries are run (in emulation) during cross-development. The
net result is that all the hassles and confusion of outsmarting poorly-written
portability tests are gone; you get the performance of the host system (including,
presumably, native execution of the compiler toolchain), and the behavior of the
target.
These tools, while clearly still in development, appear to be stable and
functional, and actively maintained. This may have lasting effects on the way
tools are developed for a variety of other systems. Furthermore, a good
cross-compilation environment, without some of the quirks of the more conventional
sort, helps reduce the inconvenience of a machine that frankly hasn't got the
memory or CPU to do large software builds.
The inevitable comparisons
The 770 shows some of the influences and lessons learned from the Zaurus. I noted
above the lack of a physical keyboard, but this has attracted a lot of outside
development effort. More subtle is the amount of available memory; while the 770
has more than some previous devices, it runs out fairly easily. Even a small
amount of additional memory would help a lot. On the other hand, full screen video
playback is quite the thing, and that it can be done at all is rather impressive.
The 770 doesn't have the expansion options that some PDA-type devices do, with
both CompactFlash and Secure Digital card slots. Its single expansion slot uses a
reduced form factor SD card, which admittedly fits quite nicely in a very crowded
case. On the other hand, very few PDAs can be configured to work as USB host
devices; if you're willing to put in the time and effort, the 770 can use USB hard
drives.
Because it's the size of a handheld, the 770 gets compared to various palmtop
devices. The 770 isn't a PDA. It's an Internet widget. The provided version of the
Opera Web browser is exceptional for a handheld device. It doesn't have the PIM
apps that users would expect from a PDA, but many devices that are designed as
PDAs are used primarily for other applications, such as Web and e-mail access. In
many cases, the 770 does an excellent job of replacing those, although better
keyboard support -- for conventional IR keyboards, for instance -- would have been
nice.
Nokia has put some effort and thought into making the 770 friendly to hobbyists
and hackers, but the default install doesn't contain any kind of shell; this is a
noticeable difference from, say, the Zaurus. The presented interface is more like
a simplified Internet kiosk than a desktop workstation. Like the TiVo, the 770
doesn't require that you know or care that you're running Linux to make effective
use of its basic features. Unlike the TiVo, it welcomes you to make use of Linux
to add your own features.
Where are they going with this?
In researching this article, I read a lot of reviews of the 770, and my impression is that a lot of people are not quite sure what it is. For as much as
everyone said they wanted a tablet-based Web browser, a lot of people are unsure
what to do with it.
The 770 shines as a device for looking things up on the Web, given Wi-Fi or
Bluetooth access. It also has great potential as a development target for custom
applications; for instance, it would make an excellent wireless sniffer.
Despite any uncertainty as to the 770's intent, Nokia has been doing some
significant research; they developed an entire, new cross-compilation architecture
that is most visibly used with the 770. The developer-friendly environment seems
to have brought a lot of casual hackers into the field, and the feedback and
patches these developers generate will certainly improve the development
environment. Even if it isn't all that successful directly, the 770 is
contributing substantially to the world of embedded Linux development, and may
make future Linux-based devices better and less expensive as a result.
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About the author | 
| | Peter Seebach has been using computers for years and is gradually becoming acclimated. He still doesn't know why mice need to be cleaned so often, though. |
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