Re: Future devfs plans

From: Erik Steffl
Date: Mon Jul 26 2004 - 02:01:46 EST


Andreas Jellinghaus wrote:
On Mon, 26 Jul 2004 00:34:51 +0000, RamÃn Rey Vicente wrote:

With udev you can do that, and without important bugs :). And the more
important thing is _udev is in active development_


devfs has the "open /dev/somefile" to load $somedriver
mechanism. it is said to be racy, as far as I know.

udev works very differently. mostly, the idea is kernel detects hardware,
kernel calls hotplug, hotplug loads driver, driver registers device
structure in kernel, kernel calls hotplug for the new device, udev creates
the device in /dev.

with this mechanism, the kernel always has all drivers for hardware
currently available loaded, and udev provides the /dev devices.

devfs allowes you to not have the driver loaded till you try to use it.
so udev _cannot_ do what devfs does.

still I agree that the way kernel/hotplug/udev work is much better and
supporting the old style devfs works is not necessary. but please be
honest about the differences.

which means that now iPod automatically connects to firewire (and looses info on random tracks, sometime some other settings), instead of only connecting when I try to actually access it (the device).

it looks like there is no user level (end user, not admin) control on when the device drivers are loaded anymore - or is there?

Is there any way to load drivers on demand (obviously it's not job of udev but whose job it is?). What about unloading them - I unmount the disk and i think the iPod is disconnecred but it still says connected - is there any way to disconnect it (I guess similar problems arise with other hotplug devices)

erik
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