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your Gumstix’s root filesystem. At this point, Xfbdev finally

is on the system. We’re almost at the finish line. On your

Gumstix console, load the drivers we copied earlier:

# cd /mnt/mmc

# insmod drivers/video/syscopyarea.ko &&

insmod drivers/video/sysfillrect.ko &&

insmod drivers/video/sysimgblt.ko &&

insmod drivers/video/fb_sys_fops.ko

# insmod drivers/video/metronomefb.ko

# insmod drivers/video/am200epd.ko

fb1: Metronome frame buffer device, using 505K of video memory

The fb1 kernel message indicates that we now have a

real framebuffer device to play with. Now, we need to point

Xfbdev at the right device, so enter this:

# # make fb0 actually become fb1

# rm /dev/fb0

# mknod /dev/fb0 c 29 1

# /usr/X11R6/bin/Xfbdev -ac &

At this point, you should see the familiar crosshatch pattern

of X. Yes, we finally did it! We now have an X11-enabled

E-Ink display.

What to do next? Well, the Gumstix device has USB-net

support, which means you now have a remote X11 display

that you can connect to from any other machine on the net-

work. You can point any X11 application at it—for example:

# # 10.0.0.2 is the E-Ink display

# # Slideshow

# for i in `ls *.jpg` ; do echo $i ;

xloadimage -display 10.0.0.2:0 -global -rotate 90 $i ;

done

# # PDF slideshow

# (( i = 1 )) ; while (( $i < 21 )) ; do echo $i ;

xpdf -remote eink /tmp/mybook.pdf $i -display 10.0.0.2:0 ;

sleep 3 ; (( i = $i + 1 )) ; done

# # Remote display an Ubuntu desktop on your E-Ink display

# DISPLAY=10.0.0.2 vncviewer ubuntu_box:1

The Future

A lot of work has been going on to enrich the Gumstix

toolset and provide better integration with the AM200 kit.

Projects like OpenEmbedded are simplifying embedded

Linux work. I see a bright future for these displays (no pun

intended). I don’t think it will be much longer before we

have displays that we can roll up just like paper and stuff

in our back pockets. The costs will come down, and we’ll

be able to scatter them on a desk just like regular paper

and treat them as extensions of our normal desktop display.

Linux will continue to be at the forefront of this with its

unique capabilities.

Acknowledgements

The author is grateful to E-Ink engineers for their extensive

support and hardware help, and to Andrew Morton, Peter

Zijlstra, Antonino Daplas, Paul Mundt, Geert Uytterhoeven,

Hugh Dickins, James Simmons and others for code review,

mm, fbdev and general help.

Jaya Kumar has been enjoying Linux since 1995 and is the author and maintainer of deferred IO, the

fbdev drivers for E-Ink controllers. He is on a constant lookout for chocolate kulfi as well as cool

new technologies to hack on and welcomes any and all feedback at jayakumar[email protected].

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august 2008 www.linuxjournal.com

Resources

Gumstix OE Build Details:

www.gumstix.net/Software/

view/Getting-started/Setting-up-a-build-environment/

111.html

Gumstix Buildroot Setup:

docwiki.gumstix.org/Buildroot

Using ipkg with Gumstix Feeds:

www.gumstix.net/Software/view/Getting-started/

Updating-and-adding-packages-via-ipkg/111.html

E-Ink AM200 Prototype Kit:

www.e-ink.com/kits/

am200_index.html

FEATURE Fun with E-Ink, X and Gumstix

Figure 4. Xfbdev Running on Gumstix E-Ink Figure 5. Ubuntu Desktop VNC-Viewed on a Gumstix E-Ink

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