7 Feb
2018
7 Feb
'18
10:34 p.m.
[top-post righted]
On 2/6/2018 9:06 PM, Dan Cross wrote:
On Tue, Feb 6, 2018 at 8:48 PM, Dave Horsfall <dave(a)horsfall.org> wrote:
[...]
On Wed, 7 Feb 2018, Greg 'groggy' Lehey wrote:
Wasn't that "devfs" (which Penguin/OS calls "udev")? I've
never grokked
that concept.
No. devfs was (is?) a pseudo-filesystem where only special files
corresponding to the devices enumerated by the kernel during
autoconfiguration are present. The contents are synthesized at boot time and
the filesystem is mounted at some canonical location (like /dev), but is
otherwise ephemeral. This is in contrast to the older /dev, which is usually
just a directory on the root filesystem, wherein one created a number of
device files that may (or may not) correspond to an actual hardware device
in the system (remember the old dance of, "cd /dev && ./MAKEDEV foo"
when
you added a "foo" onto your system?). The inodes and directory entries for
those files actually exist in the disk-resident filesystem structures
(though of course data blocks aren't allocated to those files and the inode
doesn't refer to any data blocks).
V3 and earlier still *called* them special files, but it seems they were
essentially just magic inode numbers (there was no physical file on disk,
just any directory entry with the given inode would be the special file).
Isn't that still the case? - Dan C.
On 7 February 2018 at 11:24, Arthur Krewat <krewat(a)kilonet.net> wrote:
medusa# mount | egrep '^/dev'
/devices on /devices read/write/setuid/devices/rstchown/dev=9640000 on Fri
Jan 19 16:33:07 2018
[...]
SunOS medusa 5.11 11.3 i86pc i386 i86pc
Further more (5.10 sun4u):
File Systems devfs(7FS)
NAME
devfs - Devices file system
DESCRIPTION
The devfs filesystem manages a name space of all devices
under the Solaris operating environment and is mounted dur-
ing boot on the /devices name space.
The /devices name space is dynamic and reflects the current
state of accessible devices under the Solaris operating
environment. The names of all attached device instances are
present under /devices.
The content under /devices is under the exclusive control of
the devfs filesystem and cannot be changed.
N.