[Voyage-linux] Several comments on Voyage 0.75

[Edwin van Drunen]

Hello,

I have been using Voyage since version 0.6.0 for many industrial systems and
have been very satisfied with it. Some custom fixes were applied to previous
versions of voyage that don't work anymore in 0.7.5 and I found several
issues with version 0.7.5 that maybe can be easily fixed in the base image:

### Problem: CF card is /dev/sda instead of /dev/hda
When using the voyage 0.7.5 live CD to PXE boot an Alix 2D13 board, the
compact flash card is recognised as /dev/sda.
The automated installer assumes the CF card to be /dev/hda and therefore the
installer won't work. It has to be installed manually using voyage.update
and selecting /dev/sda as the target

After the installation is finished and the board has rebooted, the CF card
is recognised as /dev/hda.


### Timing
I had a lot of timing issues with Voyage 0.6.5 and 0.7.0.
The kernel (2.6.32-voyage) would complain that clocksource "tsc" was
unstable and use "jiffies" instead. The clock would drift with several
minutes every hour and NTP was unable to keep the clock in sync.
Since Voyage 0.65 I added "clocksource=tsc" bootparameter to grub's menu.lst
and combine it with NTP to keep the clock in sync and this worked well.

Besides that I added the following things to properly access the hardware
clock during boot on alix boards:
add "rtc" to '/etc/modules'
add "HCTOSYS_DEVICE=rtc" to '/etc/default/rcS'

The new kernel (2.6.38-voyage) now uses "pit" as clocksource on the Alix
2D13. After 10 hours the clock was 5 seconds behind. This is something that
NTP can manage. Are there any other significant differences or advantages to
using pit instead of tsc?


### Displaylink USB monitor drivers
The "udlfb" driver module for Displaylink devices is included in kernel
2.6.38. It would be nice if the module could be part of the default voyage
kernel:
Device Drivers -> Graphics support -> Support for frame buffer devices ->
Displaylink USB framebuffer support -> M

For use if the monitor in Xorg the video driver
"xserver-video-xorg-displaylink" is also needed, but this is not part of the
Debian distribution. Ubuntu does have packages and source available.
Currently I build this module on the Voyage SDK myself, but also this would
be a good addition to the Voyage distribution.


### Kernel CPU optimization
The default kernel is optimised for 486 and higher CPU's and using 586 on
the Geode LX CPU's would make performance worse.
Now there is also a Geode LX option in the kernel. Does this increase
performance or enable features otherwise not used?
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