Current snapshot of the Linux-on-Dell-Axim-X5 project

It's already half of year since I started working on this project. So its time to show up some results. Here is the first public release of the project. This not a "beta version". It's not even an "alpha prerelease", it's just a snapshot of my current work - a proof of concept. Also I hope to simplify with the release of this snapshot the efforts of those who want to try Linux on Dell Axim X5, but can't afford or don't have time for the first - most complex - step, e.g. compiling a working kernel, setting up a initrd and a root filesystem.

Also I hope with this pre-release to attract people with good Linux knowledge to work on this project. There are very little people working on it (see the Credits section): the more of us, the faster the project will move.

And a warning: back up everything before you try it. Rebooting to Linux will clear up the whole 64Mb of RAM, so WinCE will lose it's current state. Currently Linux does not touch ROM, so rest assured that in no event you will render your Axim unusable. The worst that can happen is that WinCE will be reset to a clean state (like when you do Power+Reset).

A few screenshots of Dell Axim running Linux are available here

Pre-requisites

First of all, you need a CompactFlash memory card. Currently Linux does not support SD or MMC, and since I don't own any of these cards, it's not a high priority for me. I'll try to do them, however, when I'll finish with more stringent tasks (and obviously, if I'll get an SD or MMC card).

Also you'll need a CompactFlash card reader; there are a lot of these today, and they are cheap, so it's not a big problem at all.

You must download three files: the WinCE linux loader program, the initrd and the root filesystem tarballs. The root filesystem contains all the base files of the Familiar Linux distribution plus a basic installation of Opie (see http://opie.handhelds.org).

To use these files you will need Linux on PC. Not that I'm so much of a Windows hater, but it simply lacks the required functionality. I could put up a precompiled, say, initrd, but this would limit the freedom of those who have linux and likes to change the initrd.

How to run Linux

First of all, you must repartition your CompactFlash card. Split it into two partitions, one for WinCE files and one for Linux root filesystem. The root fs must be at least 40Mb in size. Format it as ext2 (not ext3, as there is little reason to use journaled file systems on flash cards). The first partition must be formatted with the FAT file system.

If you have an USB card reader, the memory card is usually /dev/sda. If you don't have /dev/sda, you must modprobe usb-storage and sd_mod kernel modules. Now after you have inserted the card into the reader you must force Linux to re-read the partition table, since there's no hardware notification issued when you insert the card (Windows just tries to read the card continuously, that's how it 'detects' the card). For this, use the command:

hdparm -z /dev/sda

After this, you may run fdisk /dev/sda and re-partition your CompactFlash card. The startup scripts expects to see /dev/sda1 as the first FAT partition, and /dev/sda2 as the second ext2fs partition. After you boot Linux on Axim they will be seen as /dev/hda1 and /dev/hda2 respectively.

Now unpack the axim-rootfs archive to the rootfs partition. You must do this as root, otherwise the important files in /dev/ will not be created (only root can create device nodes).

After this, unpack the axim-initrd tarball (as root) to some directory on your hard drive. Now run the 'axim' script (as root), this must create a file called 'initrd' of approx. 1.5Mb size.

Finally, unpack the wince-loader archive to some directory on first CompactFlash partition. Create a directory, say 'Linux', and put HaRET.exe and the .txt files there.

Okay, now you're set up. Run HaRET and click on the Run button.

How to use Linux

After Linux boots, you can insert the PDA into the USB cradle, or use a USB sync cable. If you have hotplug set up correctly in Linux, the CDCEther driver will be automatically loaded.

After that, you can configure the new Ethernet interface that just appeared to use the address 192.168.131.102 (this is the same address that SynCE uses for the host). The PDA is configured with the address 192.168.131.201.

To automate this task, on RedHat-like systems you can create a file under /etc/sysconfig/network-scripts (mine is called 'ifcfg-eth1'):

DEVICE=eth1
ONBOOT=no
BOOTPROTO=static
IPADDR=192.168.131.102
NETMASK=255.255.255.0

After the interface is up and configured, you can ssh to the PDA. The default root password is 'rootme', like in regular Familiar distributives.

Alternatively, the PDA supports logins via the serial sync cable/cradle and via the IrDA serial port. You must set up your terminal program (I use minicom) to 115200, no flow control (neither software or hardware). For regular serial cable you must use 8N1, for IrDA use 7E1 (this is used to combat IR noise).

NOTE: if you're using IrDA NEVER use the ircomm0-99 devices for communication with the PDA - it WON'T work. You must use the plain serial device - /dev/ttyS2 in my case, or /dev/usb/tts/0 for those with USB IrDA dongles and the ir-usb driver running.

What will work

• The LCD (obviously). The framebuffer driver lacks accelerated graphics, so the graphics is a little slow (compared to wince). This is relatively easy to fix, I just don't have time for it (there are more important pending tasks).
• Backlight. Sadly enough, Opie has been designed to work with the 2.4.x series of kernels, and it is unable to control the backlight from within Opie with the 2.6.3 kernel. To manipulate backlight, you must manually read/write the pseudo-files located under /sys/class/backlight/mq11xx_fb0/ (brightness) and under /sys/class/lcd/mq11xx_fb0/ (contrast).
• Touchscreen. Thanks to Wolfson Microelectronics and Liam Girdwood, there is a Linux driver for the WM9705 CODEC used in Axim (which handles the touchscreen, along with sound).
• Sound. Not intensively tested, but at least you can hear clicks and such sort of things in Opie.
• Cradles and sync cables. Linux automatically detects when you connect the PDA to a computer. If it is a USB cradle or sync cable, the respective drivers will be automatically started. The PDA will look from computer's point of view like a USB Ethernet Card. Alas, this works only with Linux PCs at the moment; there's a RNDIS driver in the 2.6.5 kernel tree that will cope with Microsoft's own interpretation of USB Ethernet CDC standard.
• USB Device Controller, as you may have guessed from the above. There are several gadget drivers available, however I only tested with g_ether. The speed with Linux seems to be higher than with WinCE: via synce I get around 220-270k/s, with Linux I can get as much as 500k/s (PC to PDA) or 375k/s (PDA to PC). This is a speed that's easily sustained over a half of hour in one of my tests.
• CompactFlash slot (PCMCIA). Tested so far only with memory cards; you can't test it with other cards as for now CF contains the root filesystem :)
• The buttons. There is a fully functional driver for all of the Axim buttons, however Opie cannot handle most of them (in fact, the only button it recognizes is "joypad press", it acts as ENTER). This has to be investigated yet.

What won't work

• Flash ROM support. This is tightly related to supporting sleeping. Supporting sleep mode means flashing Linux into the ROM, since there's no way for Linux to handle the wake-up process (WinCE will take it over, resulting in a 'freshly reset' WinCE). There is a driver for Intel StrataFlash ROM in Linux (you can even try it - it's on the initrd), but there's a lot of work to be done yet in this area.
• SD/MMC support. This is not a high priority task for me, but it is a interesting challenge. MMC specs cost >$500, and SD specs are NDA. And last but not least, I don't have any SD nor MMC cards.
• LED support. This is a easy task, however it's very low priority. It would be nice though to be able to flash the LED programmatically. I know for sure it is possible to flash it both green and yellow colors, even when the PDA is out of cradle.

Known issues

• The touchscreen is noisy. If you run the drawpad, you may notice that when you draw a straight line the result looks like a cardiogram of a dying dog. This problem can be solved by using the pxa-ac97-wm97xx driver, but in this case sound doesn't work. This is planned to be fixed in the future.
• Opie is unstable. Well, this is the latest Opie from the unstable feed. So it crashes from time to time.
• Buttons don't work in Opie. See above the notes about the buttons driver. The driver is okay, however some glue layer is missing between the driver and the user mode; this has not been investigated yet.
• After you ssh to the PDA, even if you enter the correct root password, sometimes the session suddenly closes. I think this is somehow related to dropbear (the tiny ssh server running on PDA), perhaps it's a bug in it.

Feedback

Please don't bomb me with newbie questions. Try hard to find out yourself how to solve your problems. I have so little free time, that I won't be able to work on this project anymore if I'll have to answer more than 10 letters every day. So if your letters will be ignored, don't be surprised.

Also try to drop in to the #handhelds.org channel on irc.freenode.net. There are lots of PDA people there, that can help you with non-Dell Axim-related questions (ask Opie-specific questions on #opie). You can find me there almost every day, usually between 20:00 and 24:00 GMT-3.

My email address is (I hate spam):

echo '*np*z*~m*il:ru' | sed -e 's/~/@/' -e 's/:/./g' -e 's/*/a/g'

Contributing

If you wish to contribute, you're welcome. The project needs talented programmers and simply experienced Linux users. The current list of tasks that have to be done can be found in the