Re: RFC: Starting a stable kernel series off the 2.6 kernel

Michael Frank
2005-12-04T15:08:41Z

On Sunday 04 December 2005 05:46, Luke-Jr wrote:
> On Sunday 04 December 2005 00:20, Greg KH wrote:
> > > Switch "broken bloaty bulky devfs" to "lean & clean
> > > devfs"? This ship would have been flying the
> > > "clean-up nation" flags.
> >
> > Again, because an in-kernel devfs is not the correct
> > thing to do. devfs has been disabled for a few months
> > now, and I don't think anyone has missed it yet :)
>
> Well, devfs does have some abilities udev doesn't:
> hotplug/udev doesn't detect everything, and can result in
> rarer or non-PnP devices not being automatically
> available; devfs has the effect of trying to load a
> module when a program looks for the devices it provides--
> while it can cause problems, it does have a possibility
> to work better. Interesting effects of switching my
> desktop from devfs to udev:
> 1. my DVD burners are left uninitialized until I manually
> modprobe ide-cd or (more recently) ide-scsi
> 2. my sound card is autodetected and the drivers loaded,
> but the OSS emulation modules are omitted; with devfs,
> they would be autoloaded when an app tried to use OSS
> devfs also has the advantage of keeping the module info
> all in one place-- the kernel or the module. In
> particular, with udev the detection and /dev info is
> scattered into different locations of the filesystem.
> This can probably be fixed easily simply by having udev
> read such info from modules or via a /sys entry, though.

Seems your complaints are related to missing/broken
configuration (of your distribution).

Here are some references which may be of help:

http://webpages.charter.net/decibelshelp/LinuxHelp_UDEVPrimer.html
http://www.gentoo.org/doc/en/udev-guide.xml
http://gentoo-wiki.com/HOWTO_Customizing_UDEV
http://ubuntuforums.org/archive/index.php/t-11718.html

IME, udev is easier to manage than devfs because there are
tools such as udevtest.

Please see also manuals for udevstart udevtest, udevinfo,
udevcontrol

Also strace udevstart is interesting...