[Klug-general] DBus Problem

[Karl Lattimer]

> DBus from what I've managed to find out sounds far to complicated and
> under documentated to do its job properly. Its probably that modern
> graphical OS are complicated full stop.

I'm going to cut this down pretty succinctly, firstly D-BUS is _VERY_
well documented with the obvious tutorial;
http://dbus.freedesktop.org/doc/dbus-tutorial.html
followed by the homepage index of available documentation;
http://www.freedesktop.org/wiki/Software/dbus

secondly, D-BUS is not supposed to be a userspace tool, it is a daemon
which is started in two different ways, 
1, there is the system message bus started generally with the command;
    dbus-daemon messagebus --system
2, there is the session message bus which is started in userspace
something like this;
    dbus-launch --exit-with-session gnome-session

as far as debugging dbus there is generally no need, once started dbus
checks the supported features provided by anything installed which has
an appropriate dbus service attached which can be either putting
something on the bus, or taking something off, or both. 

D-BUS in short is a very simple method of sending signals via a service
orientated IPC (inter-process communication) which won't fail in the
event that an application isn't available to take something off, also
D-BUS isn't locked down to IPC with a single application/service at a
time instead its more of a broadcast system.

Its not very complicated at all, most of the documentation is purely
developer documentation and for good reason, there isn't really an
instance where the user needs to get involved with D-BUS. Further I'd
like to say that modern desktop OS's aren't very complicated, especially
as we now know what is going on under the hood, after years of windows
doing its thing and everybody complaining about what it was doing whilst
not understanding why/how, there is now in existence a free and open
architecture which provides the same kind of functionality albeit in a
more secure POSIX security model and most importantly because its open
you can take it apart and learn how it works.

Anyway, in order to debug your problem I'd say concentrate more on HAL
and your hardware/BIOS configuration than D-BUS. The comments in
http://www.verifysoft.net/2001/dmi_scan.c.html (the so called dell
laptops hall of shame) should shed some light on how bad some hardware
can be, specifically around line 116. 

Simplify your hardware before you begin to look for what linux is
complaining about, modify your bios and turn off anything that isn't
necessary, remove any hardware that can be removed while still providing
a functional system.

Then you should begin by starting your system in single mode simply by
appending single to your kernel boot params;

i.e. root=/dev/hda2 vga=791 single 

in grub press "a" then just type " single" without quotes.

Next thing to do would be to step through your boot process, I don't
know the details of this on ubuntu, but I'd imagine init 2 waiting then
init 3, etc upto 5 if all is well, if it crashes at runlevel 3 then
you'll probably find that that is when D-BUS and HAL are started, so
start HAL and D-BUS in the order they are supposed to start and see what
happens. If you start them independently you may see some error which is
hidden otherwise. 

Next start the system back up this time in the runlevel before the
crash, by appending for instance " 2" to your boot params rather than "
single" then you wanna look inside of your init scripts and run the
individual commands by hand without making them a background process.
You should do this on separate terminals first starting D-BUS, then HAL
by hand. 

See what happens, once you've got some detail, submit it back to the
canonical guys for review. You'll probably find that a lot of it will
already be known about and they'll point you to a fix.

Hope this helps,

 K,

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