Messages in this thread |  | | | Date | Thu, 23 Jun 2005 21:54:30 +0200 | | From | Kay Sievers <> | | Subject | Re: [GIT PATCH] Remove devfs from 2.6.12-git |
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On Wed, Jun 22, 2005 at 11:26:27PM -0700, Greg KH wrote: > On Thu, Jun 23, 2005 at 03:14:08PM +0900, Miles Bader wrote: > > Greg KH <greg@kroah.com> writes: > > > And again, for embedded systems, there are packages to build it and put > > > it in initramfs. People have already done the work for you. > > > > BTW, has anyone done a comparison of the space usage of udev vs. devfs > > (including size of code etc....)? > > Not that I know of. If you want to do this, compare the original udev > releases that were around 5kb of code, as the nice features it has today > are stuff that devfs can not support at all.
Sure, the main udev target is not the embedded world, just because there is not such a big requirement to adapt a system to so many possible changes that a desktop system or big servers seeing today.
But we have prepared the kernel with hotplug-events over netlink and a full featured environment carried with the event. Instead of whining about devfs going, start implementing your own tiny "udev" that even works without sysfs at all:
o Set /proc/sys/kernel/hotplug to "".
o Create a single daemon that listens for netlink/events. Use $MAJOR $MINOR from the environment and create a node.
o Define a simple kernel-name <-> node-name + action lookup table in the daemon If an action is defined, fork an event with the environment of the received netlink/event and handle the event externally.
o For bootup, embedded setups can probably just use the minimal required set of nodes, which are copied over to the tmpfs /dev - mount. After real userspace is up, the daemon will take care of maintaining /dev.
That way, you have a nice replacement for devfs, /sbin/hotplug and using $MODALIAS a replacement for most of the hotplug scripts.
Based on udevd.c in the current udev-tree one can do this in less than a week, still enough time before devfs is removed. :)
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