“Linux kernel version 2.3.46 introduced “device filesystem,” or
devfs, support in the official kernel tree. devfs provides a
new filesystem type to be used for /dev. This filesystem keeps
track of /dev layout and entries from within the kernel, without
using on-disk storage. This means that new entries can appear in
/dev as device drivers are loaded and new hardware is detected by
the system. This facility is marked as experimental, and its
use is expected to remain optional, as some environments (such as
embedded systems) may still prefer to use the old approach.”
“In this article I’m going to give only a brief introduction to
devfs, skipping over its setup and configuration. More detailed
documentation on those issues is available elsewhere; one good
source of information, for instance, is the file
Documentation/filesystems/devfs/README found in newer kernel source
trees.”
“I’ll show how device programmers can write code that fits in
with the devfs environment. The discussion and sample code here are
based on version 2.2.14 of the kernel, which has been patched with
devfs-patch-v99.11.gz, available from
ftp//ftp.atnf.csiro.au/pub/people/rgooch/linux.”