Linux Laptops & Projectors How-To

[Dennis Kibbe]

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If you're had trouble connecting your Linux laptop to a projector at a
PLUG meeting or as we did at the Desert Code Camp this weekend you may
find this tutorial helpful.

The reason you cannot get an image from the projector is that the laptop
is using a video mode that the projectoe doesn't understand so you get
just a blank screen or at most a few flickers.

What needs to be done is to set the laptop to a video that is compatible
with the projector. You can't do this from within GNOME or KDe but must
do it at the time the kernel boots by adding a video mode option. This
tutorial will show you how.

First, connect the projector to the laptop while the laptop is still
off. Then turn on the projector and make sure it;s looking at the
correct input source. There may be more than one. (EX: video, Computer1,
Computer2). At this point the projector will show only a blue screen,
most likely, and that there is no signal coming from the input source.

Now turn on the laptop. The first thing you'll see is the BIOS loading
and often the manufacturer's splash screen (Dell, Compaq, etc.). Next
LILO or GRUB will start usually with a short pause to give you time to
choose a kernel or add boot options, which is exactly what we want to do.

Distros like Ubuntu or Fedora make this job very easy. When the Ubuntu
logo shows on the screen you'll see some options across the bottom of
the screen. Pressing F4 (VGA) lets you select a different video mode.
You want to choose either 600x600x16 or 1024x768x16 depending on what
video mode the projector recognizes. If you guess correctly you should
see the rest of the boot process (if you are in framebuffer mode). You
may need to toggle between the laptop LCD and the projector using the
function key on your keyboard (on my Dell, it's funxtion F8). If the
screen remains blank with only a flicker or two then the video mode is
too high and you need to reboot and select a lower VGA mode.

If the projector shows a blue screen and the words "No Signal" you've
selected the wrong input source.

If you distro doesn't have convenient selection options like the Ubuntu
example then you need to add the video mode option by hand.

In LILO tap the tab key and you'll see a menu of kernels available to
boot. In my case they are Linux and Linux-SMP. So at the prompt I would type

Linux-SMP vga=0x317

to boot into 1024x768x16

or

Linux-SMP vga-0x314

to boot into 800x600x16

You could also edit /etc/lilo.conf to add this boot option to a new
stanza. Be sure to run "lilo -v" after you save your changes and check
for any warnings.

If your distro uses GRUB as the boot loader you can type "a" to append
an option at book time and like LILO you could add an entry in the GRUB
menu so you can boot in "projector mode".

Once you have the KDE or GNOME desktop showing on the monitor you may
still need to use the resize applet to resize it down if your mouse can
move off the screen.

Dennisk
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