On Wednesday 06 April 2005 21:55, Christian Parpart wrote:
On Wednesday 06 April 2005 11:42 pm, Karl Zander wrote:
I was going to upgrade to a 2.6 kernel, but then found out I really
should stay with a 2.4 kenel. (The 2.6.x Win4Lin sources I need are hard
masked in portage.) I had already emerged udev before I checked this. My bad for not checking. But can I go back to devfs? How? Do I need
to?
Um, yeah, you can. Of course. But why do you want to? (see /etc/conf.d/rc at RC_DEVICES="devfs" / ="udev")
udev is less tested and doesn't work "out of the box"
What do you need, you believe devfs can, but udev can't?
Automatic module loading, for one. Devfs will load the modules needed when you try to access a device (eg /dev/cdroms/*). With udev, you need to load modules to use them. While cold/hotplug will detect and load many modules, it also lacks detection for many common devices (such as IDE CDROM drives).
And, no, I don't consider modules.autoload (or whatever file it is) to be a solution. More of a bad hack to workaround bad detection. Thus, I don't intend to have any of my systems make use of it.
Greg Kroah-Hartman addresses this complaint in the FAQ:
http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev-FAQ
and frankly I think it makes sense. He states that udev is intended to manage device nodes and nothing else and that "all devices present on the system should generate hotplug events, loading the appropriate driver". That seems fair enough to me; let it do one job and do it well.
His assertion about the problematic nature of the "devfs approach" is quite right. I've had my fair share of nasty "append to parent" errors and other wierdness with devfs, particularly in 2.6. I also heard from a developer who had some serious issues when trying to perform various LVM2 related options ... until he moved to udev. And udev has some tricks up its sleeve too (a simple way of having a consistent naming policy for devices, for one).
Regardless of the relative merits, the maintainer has gone AWOL and devfs is on the way out. I would much rather use udev in 2.6, although devfs is more functional in 2.4.
Regards,
--Kerin Francis Millar -- [email protected] mailing list
