Re: [gentoo-user] Re: New xorg.conf with x11-base/xorg-server-1.5.3-r5

[Alan McKinnon <alan.mckinnon@gmail.com>]

On Saturday 16 May 2009 19:14:17 pk wrote:
> Alan McKinnon wrote:
> > I'm not sure who's criticizing DeviceKit, but it isn't me :-)
>
> I guess it was me... :-)
>
> I find this thread interesting:
> http://lists.freedesktop.org/archives/xorg/2009-May/045561.html
>
> ...especially this:
> http://lists.freedesktop.org/archives/xorg/2009-May/045574.html
>
> Which seems like a much more sane way... to me. I don't know what BSD
> and other platforms use (instead of Udev) but I'm sure one could come up
> with a common API.

Sometimes you have to make several horrendous errors to know what to not do 
and thereby deduce what you should do - the only version 3 rule of thumb :-)

From threads involving the hal maintainers I get the idea that the problem is 
not so much the idea of hal, but rather it's implementation. And then there's 
those fdi files...

As I see it, at the bottom of the stack you have a kernel and at the top a 
user space app (the X server will do for an example). Plug in a USB device 
that the app can use, and the kernel needs to make a node in /dev for it if 
it's not already there. The kernel should not be interrogating the device for 
all possible info - that is expensive - and doesn't need to. It only needs 
enough info to know what driver, major and minor numbers to use. X OTOH, can 
successfully use much more info. If you have a 19 button mouse, it would like 
to know and could even use it as a one-handed keyboard (extreme example). So 
the current model uses udev as the interface to the kernel's nodes and HAL as 
the interface to exactly what hardware you have. Seems pretty sane for the 
most usual use case. At some point in the stack you will need the OS-dependant 
part, my guess is the best place is between hal and udev. Only Linux uses 
udev, but all OSes use something in that spot. And if not, they have static 
nodes.

Meanwhile we have an acknowledged problem with hal - it's too complex, too 
many things have been shoved into it that were never catered for in the 
design, configuration is horrific - and the devs are having their usual 
spirited debate about how best to approach a solution. This is perfectly 
normal and perfectly healthy

-- 
alan dot mckinnon at gmail dot com