[NCLUG] Disappearing Hardware?

[Bob Proulx]

Rich Young wrote:
> My linux-at-home experiment is on the rocks lately.  What I've been
> finding is that some devices will "just work" on the first boot after
> they are installed, but then they don't work at all after booting again.

Sorry, no answers, just questions.

> In one case (modem) the machine can't even find the hardware.

What type of modem?  An honest to goodness serial port modem?  Or a
"Win-modem" that needs a special driver?  Or???

[For modems I rather only believe in honest to goodness serial port
modems.  If it is a serial port modem I could probably help.  If not
well...  Good luck!]

> In another (printer) it acts like it's working but I never get any
> print.

I never print anything so will be worthless for that problem.

> Can anyone account for why I'd see this behavior?  I'm running Fedora
> Core 3 (KRUD) on a 1.5GHz Athlon box
> 
> A more general question closely related: So that I can be more
> self-sufficient, where does one look for the clues to problems like
> this?  /var/log/messages seems to have some info, but when I can't get
> online to google them (because the modem stopped working!), I'm kinda
> helpless.

If something works when first installed but then not after a reboot
then I am drawn to something being different between those two times.

  lsmod > lsmod.out.1

Look for what modules are installed.  Then reboot.  Then look again.

  lsmod > lsmod.out.2

If something is different then you have a clue as to why things are
not working later.

The kudzu program is a hardware discovery program.  It runs at boot
time.  It could be the install program loads a module or sets a
configuration which is not repeated at boot time.  Or kudzu might be
overriding the configuration.  All kinds of possibilities.

The dmesg command dumps (prints) the kernel message buffer.  That can
contain useful information in addition to the messages in the syslog.

Using 'lspci' one can see the hardware devices on the pci bus.  These
usually give the clues as to what type of driver for a device is
needed.  Of course sound cards and network cards are usually found
there.  But also USB devices too.  If you have a USB printer this may
come into play.

Crazy idea but I would verify that you are running the same kernel
after the install and after the reboot.  If you install a kernel
module from one but end up booted into another then that could be a
problem.  Use uname for this.

  uname -r

If it is a network printer then network firewalls may come into play.
I have often seen problems with fresh installations where a simple
check of a security setting can enable a restrictive firewall that has
caused me problems on the reboot.

With all of the above in consideration I am suspecting that upon
installation a kernel module is being loaded.  Upon reboot that module
is not being loaded.  It is not being recognized by kudzu at boot
time.  And so it is not working after the reboot.  You can explicitly
load modules at boot time by placing the module name in /etc/modules.
(Or is there a more preferred way when using RH/KRUD?)  You can
manually load modules with 'modprobe'.

Hope that helps,
Bob