Lines Matching full:devices
26 .b "Rethinking /dev and devices in the UNIX kernel"
41 implementation of the ``devices as files'' concept, an implementation which
43 Starting from a high-level view of devices and the semantics that
57 I/O devices in an operating system:
60 The usual way is to treat I/O devices as their own class of things,
62 to the semantics of the devices.
85 There is a threefold advantage in treating I/O devices this way:
182 devices into their computers.
183 These devices can be anything from modems and disks to GPS receivers
186 correct set of special devices in ``/dev'' became a major headache.
192 devices they have found in the configuration, so all that is needed is
197 .sh 1 "Truly understanding devices"
261 subset of devices like /dev/null, /dev/zero and /dev/tty,
262 whereas access to other devices such as /dev/kmem
267 of devices, ``block'' and
269 devices would provide caching and alignment for disk device access.
273 The argument that block devices were a mistake is really very
274 very simple: Many devices other than disks have multiple modes
279 and /dev/nrmt devices for tape access.\**
285 Tapes, asynchronous ports, line printer ports and many other devices
300 In FreeBSD block devices were not even implemented in a fashion
304 were found to be in existence which relied on block devices
306 block devices were removed from the FreeBSD system.
311 .sh 1 "Files, sockets, pipes, SVID IPC and devices"
332 Devices land somewhere in the middle between pipes and sockets on
338 Devices are in fact special-cased all the way through the vnode system.
339 For one thing devices break the ``one file-one vnode''
370 devices in ``/dev'', so some kind of state will have to be kept per
371 chroot(2)/jail(2) about which devices are visible and
372 which devices are hidden, but no obvious location for this information
460 issue is that when the system boots, we cannot know what devices we
461 will find, and we can not know if the devices we do find
472 device ``/dev/sio0'', but we boot and do not find any sio devices?
527 Pseudo-devices like pty, tun and bpf,
528 but also some real devices, may not pre-emptively create entries for all
534 For pseudo-devices the task at hand is to make a magic device node,
548 Some UNIX systems have solved the problem for pseudo-devices by
549 creating magic cloning devices like ``/dev/tcp''.
584 Modern sound devices have multiple channels, presumably to allow the
588 since they have no concept of multiple sound devices.
597 .sh 2 "Deleting and recreating devices"
612 The obvious way to recreate deleted devices is to let mknod(2) do it
622 Obviously, it would not be desirable for dynamic devices to pop
624 possible to mark a DEVFS mountpoint as ``no new devices''.
634 DEVFS mountpoint to the ``normal set'' of devices for a jail and
635 automatically hide all future devices and make it impossible
640 devices from appearing and will make it impossible to
667 This is mainly for use in the few system calls which knows about devices:
683 \** Basically, devices should have been moved up with sockets and
781 This is very convenient for devices which have a ``control''
793 determined how many softc structures and therefore devices
805 .sh 2 "Creating and destroying devices"
807 Ideally, devices should only be created and
808 destroyed by the device drivers which know what devices are present.
940 devices.
944 devices the kernel can deal with.
1053 In foo_attach() we can now attach to all the devices we can
1078 could configure and de-configure devices as they come and go.
1085 In this context it is good to question how we view dynamic devices.
1090 we have a database of known disk-like devices to tell us where to
1112 which allow the user to set the wanted policy for new devices.
1113 Such a mechanism could also be used to filter new devices for mount
1121 The facility for on-demand creation of devices has some very interesting
1150 Another use could be to access devices by parameter rather than by
1158 pseudo-devices and on-demand device node creation.
1232 \fI``I have not used block devices since I wrote FFS and that