5 The udev-acl extra is no longer enabled by default now. To enable it,
6 --enable-udev_acl needs to be given at ./configure time. On systemd
7 systems, the udev-acl rules prevent it from running as the functionality
14 Udev now enables kernel media-presence polling if available. Part
15 of udisks optical drive tray-handling moved to cdrom_id: The tray
16 is locked as soon as a media is detected to enable the receiving
17 of media-eject-request events. Media-eject-request events will
20 Libudev enumerate is now able to enumerate a subtree of a given
23 The mobile-action-modeswitch modeswitch tool was deleted. The
24 functionality is provided by usb_modeswitch now.
30 The systemd service files require systemd version 28. The systemd
31 socket activation make it possible now to start 'udevd' and 'udevadm
36 Fix bug in control message handling, which can lead to a failing
37 udevadm control --exit. Thanks to Jürg Billeter for help tracking
44 We require at least Linux kernel 2.6.32 now. Some platforms might
45 require a later kernel that supports accept4() and similar, or
46 need to backport the trivial syscall wiring to the older kernels.
48 The hid2hci tool moved to the bluez package and was removed.
50 Many of the extras can be --enable/--disabled at ./configure
51 time. The --disable-extras option was removed. Some extras have
52 been disabled by default. The current options and their defaults
53 can be checked with './configure --help'.
59 Udev logs a warning now if /run is not writable at udevd
60 startup. It will still fall back to /dev/.udev, but this is
63 The running udev daemon can now cleanly shut down with:
64 udevadm control --exit
66 Udev in initramfs should clean the state of the udev database
67 with: udevadm info --cleanup-db which will remove all state left
68 behind from events/rules in initramfs. If initramfs uses
69 --cleanup-db and device-mapper/LVM, the rules in initramfs need
70 to add OPTIONS+="db_persist" for all dm devices. This will
71 prevent removal of the udev database for these devices.
73 Spawned programs by PROGRAM/IMPORT/RUN now have a hard timeout of
74 120 seconds per process. If that timeout is reached the spawned
75 process will be killed. The event timeout can be overwritten with
78 If systemd is used, udev gets now activated by netlink data.
79 Systemd will bind the netlink socket which will buffer all data.
80 If needed, such setup allows a seemless update of the udev daemon,
81 where no event can be lost during a udevd update/restart.
82 Packages need to make sure to: systemctl stop udev.socket udev.service
83 or 'mask' udev.service during the upgrade to prevent any unwanted
84 auto-spawning of udevd.
85 This version of udev conflicts with systemd version below 25. The
86 unchanged service files will not wirk correctly.
92 The udev runtime data moved from /dev/.udev/ to /run/udev/. The
93 /run mountpoint is supposed to be a tmpfs mounted during early boot,
94 available and writable to for all tools at any time during bootup,
95 it replaces /var/run/, which should become a symlink some day.
97 If /run does not exist, or is not writable, udev will fall back using
100 On systemd systems with initramfs and LVM used, packagers must
101 make sure, that the systemd and initramfs versions match. The initramfs
102 needs to create the /run mountpoint for udev to store the data, and
103 mount this tmpfs to /run in the rootfs, so the that the udev database
104 is preserved for the udev version started in the rootfs.
106 The command 'udevadm info --convert-db' is gone. The udev daemon
107 itself, at startup, converts any old database version if necessary.
109 The systemd services files have been reorganized. The udev control
110 socket is bound by systemd and passed to the started udev daemon.
111 The udev-settle.service is no longer active by default. Services which
112 can not handle hotplug setups properly need to actively pull it in, to
113 act like a barrier. Alternatively the settle service can be unconditionally
114 'systemctl'enabled, and act like a barrier for basic.target.
116 The fstab_import callout is no longer built or installed. Udev
117 should not be used to mount, does not watch changes to fstab, and
118 should not mirror fstab values in the udev database.
124 New and updated keymaps.
130 The udev database has changed, After installation of a new udev
131 version, 'udevadm info --convert-db' should be called, to let the new
132 udev/libudev version read the already stored data.
134 udevadm now supports quoting of property values, and prefixing of
136 $ udevadm info --export --export-prefix=MY_ --query=property -n sda
139 MY_DEVNAME='/dev/sda'
143 libudev now supports:
144 udev_device_get_is_initialized()
145 udev_enumerate_add_match_is_initialized()
146 to be able to skip devices the kernel has created , but udev has
149 libudev now supports:
150 udev_device_get_usec_since_initialized()
151 to retrieve the "age" of a udev device record.
153 GUdev supports a more generic GUdevEnumerator class, udev TAG
154 handling, device initialization and timestamp now.
156 The counterpart of /sys/dev/{char,block}/$major:$minor,
157 /dev/{char,block}/$major:$minor symlinks are now unconditionally
158 created, even when no rule files exist.
160 New and updated keymaps.
166 GUdev moved from /usr to /.
176 Persistent network naming rules are disabled inside of Qemu/KVM now.
178 New and updated keymaps.
180 Udev gets unconditionally enabled on systemd installations now. There
181 is no longer the need to to run 'systemctl enable udev.service'.
195 New and fixed keymaps.
197 Install systemd service files if applicable.
203 All distribution specific rules are removed from the udev source tree,
204 most of them are no longer needed. The Gentoo rules which allow to support
205 older kernel versions, which are not covered by the default rules anymore
206 has moved to rules/misc/30-kernel-compat.rules.
212 The option --debug-trace and the environemnt variable UDEVD_MAX_CHILDS=
213 was removed from udevd.
215 Udevd now checks the kernel commandline for the following variables:
216 udev.log-priority=<syslog priority>
217 udev.children-max=<maximum number of workers>
218 udev.exec-delay=<seconds to delay the execution of RUN=>
219 to help debuging coldplug setups where the loading of a kernel
220 module crashes the system.
222 The subdirectory in the source tree rules/packages has been renamed to
223 rules/arch, anc contains only architecture specific rules now.
233 Now the udev daemon itself, does on startup:
234 - copy the content of /lib/udev/devices to /dev
235 - create the standard symlinks like /dev/std{in,out,err},
236 /dev/core, /dev/fd, ...
237 - use static node information provided by kernel modules
238 and creates these nodes to allow module on-demand loading
239 - possibly apply permissions to all ststic nodes from udev
240 rules which are annotated to match a static node
242 The default mode for a device node is 0600 now to match the kernel
243 created devtmpfs defaults. If GROUP= is specified and no MODE= is
244 given the default will be 0660.
250 Udev now gradually starts to pass control over the primary device nodes
251 and their names to the kernel, and will in the end only manage the
252 permissions of the node, and possibly create additional symlinks.
253 As a first step NAME="" will be ignored, and NAME= setings with names
254 other than the kernel provided name will result in a logged warning.
255 Kernels that don't provide device names, or devtmpfs is not used, will
256 still work as they did before, but it is strongly recommended to use
257 only the same names for the primary device node as the recent kernel
258 provides for all devices.
262 Fix broken firmware loader search path.
268 "udevadm trigger" defaults to "change" events now instead of "add"
269 events. The "udev boot script" might need to add "--action=add" to
270 the trigger command if not already there, in case the initial coldplug
271 events are expected as "add" events.
273 The option "all_partitons" was removed from udev. This should not be
274 needed for usual hardware. Udev can not safely make assumptions
275 about non-existing partition major/minor numbers, and therefore no
276 longer provide this unreliable and unsafe option.
278 The option "ignore_remove" was removed from udev. With devtmpfs
279 udev passed control over device nodes to the kernel. This option
280 should not be needed, or can not work as advertised. Neither
281 udev nor the kernel will remove device nodes which are copied from
282 the /lib/udev/devices/ directory.
284 All "add|change" matches are replaced by "!remove" in the rules and
285 in the udev logic. All types of events will update possible symlinks
286 and permissions, only "remove" is handled special now.
288 The modem modeswitch extra was removed and the external usb_modeswitch
289 program should be used instead.
291 New and fixed keymaps.
301 Kernels with SYSFS_DEPRECATED=y are not supported since a while. Many users
302 depend on the current sysfs layout and the information not available in the
303 deprecated layout. All remaining support for the deprecated sysfs layout is
308 Fix for a possible endless loop in the new input_id program.
314 The option "ignore_device" does no longer exist. There is no way to
315 ignore an event, as libudev events can not be suppressed by rules.
316 It only prevented RUN keys from being executed, which results in an
317 inconsistent behavior in current setups.
319 BUS=, SYSFS{}=, ID= are long deprecated and should be SUBSYSTEM(S)=,
320 ATTR(S){}=, KERNEL(S)=. It will cause a warning once for every rule
323 The support for the deprecated IDE devices has been removed from the
324 default set of rules. Distros who still care about non-libata drivers
325 need to add the rules to the compat rules file.
327 The ID_CLASS property on input devices has been replaced by the more accurate
328 set of flags ID_INPUT_{KEYBOARD,KEY,MOUSE,TOUCHPAD,TABLET,JOYSTICK}. These are
329 determined by the new "input_id" prober now. Some devices, such as touchpads,
330 can have several classes. So if you previously had custom udev rules which e. g.
331 checked for ENV{ID_CLASS}=="kbd", you need to replace this with
332 ENV{ID_INPUT_KEYBOARD}=="?*".
338 To support DEVPATH strings larger than the maximum file name length, the
339 private udev database format has changed. If some software still reads the
340 private files in /dev/.udev/, which it shouldn't, now it's time to fix it.
341 Please do not port anything to the new format again, everything in /dev/.udev
342 is and always was private to udev, and may and will change any time without
345 Multiple devices claiming the same names in /dev are limited to symlinks
346 only now. Mixing identical symlink names and node names is not supported.
347 This reduces the amount of data in the database significantly.
349 NAME="%k" causes a warning now. It's is and always was completely superfluous.
350 It will break kernel supplied DEVNAMEs and therefore it needs to be removed
353 Most NAME= instructions got removed. Kernel 2.6.31 supplies the needed names
354 if they are not the default. To support older kernels, the NAME= rules need to
355 be added to the compat rules file.
357 Symlinks to udevadm with the old command names are no longer resolved to
358 the udevadm commands.
360 The udev-acl tool got adopted to changes in ConsoleKit. Version 0.4.1 is
363 The option "last_rule" does no longer exist. Its use breaks too many
364 things which expect to be run from independent later rules, and is an idication
365 that something needs to be fixed properly instead.
367 The gudev API is no longer marked as experimental,
368 G_UDEV_API_IS_SUBJECT_TO_CHANGE is no longer needed. The gudev introspection
369 is enabled by default now. Various projects already depend on introspection
370 information to bind dynamic languages to the gudev interfaces.
376 The udevadm trigger "--retry-failed" option, which is replaced since quite
377 a while by "--type=failed" is removed.
379 The failed tracking was not working at all for a few releases. The RUN
380 option "ignore_error" is replaced by a "fail_event_on_error" option, and the
381 default is not to track any failing RUN executions.
383 New keymaps, new modem, hid2hci updated.
387 Fix possible crash in udevd when worker processes are busy, rules are
388 changed at the same time, and workers get killed to reload the rules.
394 Properties set with ENV{.FOO}="bar" are marked private by starting the
395 name with a '.'. They will not be stored in the database, and not be
396 exported with the event.
398 Firmware files are looked up in:
399 /lib/firmware/updates/$(uname -r)
400 /lib/firmware/updates
401 /lib/firmware/$(uname -r)
405 ATA devices switched the property from ID_BUS=scsi to ID_BUS=ata.
406 ata_id, instead of scsi_id, is the default tool now for ATA devices.
412 The configure options have changed because another library needs to be
413 installed in a different location. Instead of exec_prefix and udev_prefix,
414 libdir, rootlibdir and libexecdir are used. The Details are explained in
417 Event processes now get re-used after they handled an event. This reduces
418 the number of forks and the pressure on the CPU significantly, because
419 cloned event processes no longer cause page faults in the main daemon.
420 After the events have settled, a few worker processes stay around for
421 future events, all others get cleaned up.
423 To be able to use signalfd(), udev depends on kernel version 2.6.25 now.
424 Also inotify support is mandatory now to run udev.
426 The format of the queue exported by the udev damon has changed. There is
427 no longer a /dev/.udev/queue/ directory. The current event queue can be
428 accessed with udevadm settle and libudedv.
430 Libudev does not have the unstable API header anymore. From now on,
431 incompatible changes will be handled by bumping the library major version.
433 To build udev from the git tree gtk-doc is needed now. The tarballs will
434 build without it and contain the pre-built documentation. An online copy
436 http://www.kernel.org/pub/linux/utils/kernel/hotplug/libudev/
438 The tools from the udev-extras repository have been merged into the main
439 udev repository. Some of the extras have larger external dependencies, and
440 they can be disabled with the configure switch --disable-extras.
446 The program vol_id and the library libvolume_id are removed from the
447 repository. Libvolume_id is merged with libblkid from the util-linux-ng
448 package. Persistent disk links for label and uuid depend on the
449 util-linux-ng version (2.15) of blkid now. Older versions of blkid
450 can not be used with udev.
452 Libudev allows to subscribe to udev events. To prevent unwanted messages
453 to be delivered, and waking up the subscribing process, a filter can be
454 installed, to drop messages inside a kernel socket filter. The filters
455 match on the <subsytem>:<devtype> properties of the device.
456 This is part of the ongoing effort to replace HAL, and switch current
457 users over to directly use libudev.
458 Libudev is still marked as experimental, and its interface might
459 eventually change if needed, but no major changes of the currently exported
460 interface are expected anymore, and a first stable release should happen
463 A too old kernel (2.6.21) or a kernel with CONFIG_SYSFS_DEPRECATED
464 is not supported since while and udevd will log an error message at
465 startup. It should still be able to boot-up, but advanced rules and system
466 services which depend on the information not available in the old sysfs
467 format will fail to work correctly.
469 DVB device naming is supplied by the kernel now. In case older kernels
470 need to be supported, the old shell script should be added to a compat
477 The processed udev events get send back to the netlink socket. Libudev
478 provides access to these events. This is work-in-progress, to replace
479 the DeviceKit daemon functionality directly with libudev. There are
480 upcoming kernel changes to allow non-root users to subcribe to these
487 "udevadm settle" now optionally accepts a range of events to wait for,
488 instead of waiting for "all" events.
494 The installed watch for block device metadata changes is now removed
495 during event hadling, because some (broken) tools may be called from udev
496 rules and (wrongly) open the device with write access. After the finished
497 event handling the watch is restored.
503 Device nodes can be watched for changes with inotify with OPTIONS="watch".
504 If closed after being opened for writing, a "change" uevent will occur.
505 /dev/disk/by-{label,uuid}/* symlinks will be automatically updated.
511 The udevadm test command has no longer a --force option, nodes and symlinks
512 are always updated with a test run now.
514 The udevd daemon can be started with --resolve-names=never to avoid all user
515 and group lookups (e.g. in cut-down systems) or --resolve-names=late to
516 lookup user and groups every time events are handled.
522 We are currently merging the Ubuntu rules in the udev default rules,
523 and get one step closer to provide a common Linux /dev setup, regarding
524 device names, symlinks, and default device permissions. On udev startup,
525 we now expect the following groups to be resolvable to their ids with
527 disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem.
528 LDAP setups need to make sure, that these groups are always resolvable at
529 bootup, with only the rootfs mounted, and without network access available.
531 Some systems may need to add some new, currently not used groups, or need
532 to add some users to new groups, but the cost of this change is minimal,
533 compared to the pain the current, rather random, differences between the
534 various distributions cause for upstream projects and third-party vendors.
536 In general, "normal" users who log into a machine should never be a member
537 of any such group, but the device-access should be managed by dynamic ACLs,
538 which get added and removed for the specific users on login/logout and
539 session activity/inactivity. These groups are only provided for custom setups,
540 and mainly system services, to allow proper privilege separation.
541 A video-streaming daemon uid would be a member of "audio" and "video", to get
542 access to the sound and video devices, but no "normal" user should ever belong
543 to the "audio" group, because he could listen to the built-in microphone with
544 any ssh-session established from the other side of the world.
546 /dev/serial/by-{id,path}/ now contains links for ttyUSB devices,
547 which do not depend on the kernel device name. As usual, unique
548 devices - only a single one per product connected, or a real
549 USB serial number in the device - are always found with the same
550 name in the by-id/ directory.
551 Completely identical devices may overwrite their names in by-id/
552 and can only be found reliably in the by-path/ directory. Devices
553 specified by by-path/ must not change their connection, like the
554 USB port number they are plugged in, to keep their name.
556 To support some advanced features, Linux 2.6.22 is the oldest supported
557 version now. The kernel config with enabled SYSFS_DEPRECATED is no longer
558 supported. Older kernels should still work, and devices nodes should be
559 reliably created, but some rules and libudev will not work correctly because
560 the old kernels do not provide the expected information or interfaces.
566 Fix for a possible segfault while swapping network interface names in udev
573 The group "video" is part of the default rules now.
577 Bugfix for kernels using SYSFS_DEPRECATED* option and finding parent
578 block devices in some cases. No common distro uses this option anymore,
579 and we do not get enough testing for this and recent udev versions. If
580 this option is not needed to run some old distro with a new kernel,
581 it should be disabled in the kernel config.
583 Bugfix for the $links substitution variable, which may crash if no links
584 are created. This should not happen in usual setups because we always
585 create /dev/{block,char}/ links.
587 The strings of the parsed rules, which are kept in memory, no longer
588 contain duplicate entries, or duplicate tails of strings. This, and the
589 new rules parsing/matching code reduces the total in-memory size of
590 a huge distro rule sets to 0.08 MB, compared to the 1.2MB of udev
593 The export of DEVTYPE=disk/partition got removed from the default
594 rules. This value is available from the kernel. The pnp shell script
595 modprobe hack is removed from the default rules. ACPI devices have _proper_
596 modalias support and take care of the same functionality.
597 Installations which support old kernels, but install current default
598 udev rules may want to add that to the compat rules file.
600 Libvolume_id now always probes for all known filesystems, and does not
601 stop at the first match. Some filesystems are marked as "exclusive probe",
602 and if any other filesytem type matches at the same time, libvolume_id
603 will, by default, not return any probing result. This is intended to prevent
604 mis-detection with conflicting left-over signatures found from earlier
605 file system formats. That way, we no longer depend on the probe-order
606 in case of multiple competing signatures. In some setups the kernel allows
607 to mount a volume with just the old filesystem signature still in place.
608 This may damage the new filesystem and cause data-loss, just by mounting
609 it. Because volume_id can not decide which one the correct signature is,
610 the wrong signatures need to be removed manually from the volume, or the
611 volume needs to be reformatted, to enable filesystem detection and possible
616 Fix segfault if compiled without optimization and dbg() does not get
617 compiled out and uses variables which are not available.
621 Bugfixes. (And maybe new bugs. :))
623 The rule matching engine got converted from a rule list to a token
624 array which reduced the in-memory rules representation of a full
625 featured distros with thousends of udev rules from 1.2MB to 0.12 MB.
626 Limits like 5 ENV and ATTR matches, and one single instance for most
627 other keys per rule are gone.
629 The NAME assignment is no longer special cased. If later rules assign
630 a NAME value again, the former value will be overwritten. As usual
631 for most other keys, the NAME value can be protected by doing a final
632 assignment with NAME:="<value>".
634 All udev code now uses libudev, which is also exported. The library
635 is still under development, marked as experimental, and its interface
636 may change as long as the DeviceKit integration is not finished.
638 Many thanks to Alan Jenkins for his continuous help, and finding and
639 optimizing some of the computing expensive parts.
645 Kernel devices and device nodes are connected now by reverse indizes in
646 /sys and /dev. A device number retrieved by a stat() or similar, the
647 kernel device directory can be found by looking up:
648 /sys/dev/{block,char}/<maj>:<min>
649 and the device node of the same device by looking up:
650 /dev/{block,char}/<maj>:<min>
654 Fix recently introduced bug, which caused a compilation without large
655 file support, where vol_id does not recognize raid signatures at the end
658 Firewire disks now create both, by-id/scsi-* and by-id/ieee-* links.
659 Seems some kernel versions prevent the creation of the ieee-* links,
660 so people used the scsi-* link which disappeared now.
662 More libudev work. Almost all udevadm functionality comes from libudev
665 udevadm trigger has a new option --type, which allows to trigger events
666 for "devices", for "subsystems", or "failed" devices. The old option
667 --retry-failed" still works, but is no longer mentioned in the man page.
673 The udevadm info --device-id-of-file= output has changed to use
674 the obvious format. Possible current users should use the --export
675 option which is not affected.
677 The old udev commands symlinks to udevadm are not installed, if
678 these symlinks are used, a warning is printed.
684 Optical drive's media is no longer probed for raid signatures,
685 reading the end of the device causes some devices to malfunction.
686 Also the offset of the last session found is used now to probe
689 The volume_id library got a major version number update to 1,
690 some deprecated functions are removed.
692 A shared library "libudev" gets installed now to provide access
693 to udev device information. DeviceKit, the successor of HAL, will
694 need this library to access the udev database and search sysfs for
696 The library is currently in an experimental state, also the API is
697 expected to change, as long as the DeviceKit integration is not
702 We use ./configure now. See INSTALL for details. Current
705 "/usr" - prefix for man pages, include files
707 "" - the root filesystem, prefix for libs and binaries
711 "lib" - directory name for libraries, not a path name
712 multilib 64bit systems may use "lib64" instead of "lib"
714 compile-in verbose debug messages
716 disable all logging and compile-out all log strings
718 link against SELInux libraries, to set the expected context
721 In the default rules, the group "disk" gets permissions 0660 instead
722 of 0640. One small step closer to unify distro rules. Some day, all
723 distros hopefully end up with the same set of rules.
725 No symlinks to udevadm are installed anymore, if they are still needed,
726 they should be provided by the package.
732 Default udev rules, which are not supposed to be edited by the user, should
733 be placed in /lib/udev/rules.d/ now, to make it clear that they are private to
734 the udev package and will be replaced with an update. Udev will pick up rule
736 /lib/udev/rules.d/ - default installed rules
737 /etc/udev/rules.d/ - user rules + on-the-fly generated rules
738 /dev/.udev/rules.d/ - temporary non-persistent rules created after bootup
739 It does not matter in which directory a rule file lives, all files are sorted
742 To help creating /dev/root, we have now:
743 $ udevadm info --export --export-prefix="ROOT_" --device-id-of-file=/
746 In case the current --device-id-of-file is already used, please switch to
747 the --export format version, it saves the output parsing and the old
748 format will be changed to use ':' as a separator, like the format in the
753 Fix cdrom_id to properly recognize blank media.
759 Tape drive id-data is queried from /dev/bsg/* instead of the tape
760 nodes. This avoids rewinding tapes on open().
766 The symlinks udevcontrol and udevtrigger are no longer installed by
769 The scsi_id program does not depend on sysfs anymore. It can speak
770 SGv4 now, so /dev/bsg/* device nodes can be used, to query SCSI device
771 data, which should solve some old problems with tape devices, where
772 we better do not open all tape device nodes to identify the device.
778 The cdrom_id program is replaced by an advanced version, which can
779 detect most common device types, and also properties of the inserted
780 media. This is part of moving some basic functionality from HAL into
781 udev (and the kernel).
787 The last WAIT_FOR_SYSFS rule is removed from the default rules.
789 The symlinks to udevadm for the debugging tools: udevmonitor and
790 udevtest are no longer created.
792 The symlinks to the udevadm man page for the old tool names are
795 Abstract namespace sockets paths in RUN+="socket:@<path>" rules,
796 should be prefixed with '@' to indicate that the path is not a
807 Udevstart is removed from the tree, it did not get installed for
808 a long time now, and is long replaced by trigger and settle.
814 All udev tools are merged into a single binary called udevadm.
815 The old names of the tools are built-in commands in udevadm now.
816 Symlinks to udevadm, with the names of the old tools, provide
817 the same functionality as the standalone tools. There is also
818 only a single udevadm.8 man page left for all tools.
820 Tools like mkinitramfs should be checked, if they need to include
821 udevadm in the list of files.
831 The etc/udev/rules.d/ directory now contains a default set of basic
832 udev rules. This initial version is the result of a rules file merge
833 of Fedora and openSUSE. For these both distros only a few specific
834 rules are left in their own file, named after the distro. Rules which
835 are optionally installed, because they are only valid for a specific
836 architecture, or rules for subsystems which are not always used are
837 in etc/udev/packages/.
843 Dynamic rules can be created in /dev/.udev/rules.d/ to trigger
844 actions by dynamically created rules.
846 SYMLINK=="<value>" matches agains the entries in the list of
847 currently defined symlinks. The links are not created in the
848 filesystem at that point in time, but the values can be matched.
850 RUN{ignore_error}+="<program>" will ignore any exit code from the
851 program and not record as a failed event.
857 Final merge of patches/features from the Ubuntu package.
863 Control characters in filesystem label strings are no longer silenty
864 removed, but hex-encoded, to be able to uniquely identify the device
865 by its symlink in /dev/disk/by-label/.
866 If libvolume_id is used by mount(8), LABEL= will work as expected,
867 if slashes or other characters are used in the label string.
869 To test the existence of a file, TEST=="<file>" and TEST!="<file>"
870 can be specified now. The TEST key accepts an optional mode mask
871 TEST{0100}=="<is executable file>".
873 Scsi_id now supports a mode without expecting scsi-specific sysfs
874 entries to allow the extraction of cciss-device persistent properties.
880 In the future, we may see uuid's which are just simple character
881 strings (see the DDF Raid Specification). For that reason vol_id now
882 exports ID_FS_UUID_SAFE, just like ID_FS_LABEL_SAFE. For things like
883 the creation of symlinks, the *_SAFE values ensure, that no control
884 or whitespace characters are used in the filename.
886 Possible users of libvolume_id, please use the volume_id_get_* functions.
887 The public struct will go away in a future release of the library.
893 Removal of useless extras/eventrecorder.sh.
903 The directory multiplexer for dev.d/ and hotplug.d are finally removed
904 from the udev package.
910 Symlinks can have priorities now, the priority is assigned to the device
911 and specified with OPTIONS="link_priority=100". Devices with higher
912 priorities overwrite the symlinks of devices with lower priorities.
913 If the device that currently owns the link, goes away, the symlink
914 will be removed, and recreated, pointing to the next device with the
915 highest actual priority. This should make /dev/disk/by-{label,uuid,id}
916 more reliable, if multiple devices contain the same metadata and overwrite
919 The dasd_id program is removed from the udev tree, and dasdinfo, with the
920 needed rules, are part of the s390-tools now.
922 Please add KERNEL=="[0-9]*:[0-9]*" to the scsi wait-for-sysfs rule,
923 we may get the scsi sysfs mess fixed some day, and this will only catch
924 the devices we are looking for.
926 USB serial numbers for storage devices have the target:lun now appended,
927 to make it possibble to distinguish broken multi-lun devices with all
928 the same SCSI identifiers.
930 Note: The extra "run_directory" which searches and executes stuff in
931 /etc/hotplug.d/ and /etc/dev.d/ is long deprecated, and will be removed
932 with the next release. Make sure, that you don't use it anymore, or
933 provides your own implementation of that inefficient stuff.
934 We are tired of reports about a "slow udev", because these directories
935 contain stuff, that runs with _every_ event, instead of using rules,
936 that run programs only for the matching events.
946 DRIVER== will match only for devices that actually have a real
947 driver. DRIVERS== must be used, if parent devices should be
948 included in the match.
950 Libvolume_id's "linux_raid" detection needed another fix.
958 Add additional check to volume_id detection of via_raid, cause
959 some company decided to put a matching pattern all over the empty
960 storage area of their music players.
964 Fix path_id for SAS devices.
968 The udev daemon can be started with --debug-trace now, which will
969 execute all events serialized to get a chance to catch a possible
970 action that crashes the box.
972 A warning is logged, if PHYSDEV* keys, the "device" link, or a parent
973 device attribute like $attr{../file} is used, only WAIT_FOR_SYSFS rules
974 are excluded from the warning. Referencing parent attributes directly
975 may break when something in the kernel driver model changes. Udev will
976 just find the attribute by walking up the parent chain.
978 Udevtrigger now sorts the list of devices depending on the device
979 dependency, so a "usb" device is triggered after the parent "pci"
984 Revert persistent-storage ata-serial '_' '-' replacement.
990 Udevtrigger can now filter the list of devices to be triggered. Matches
991 for subsystems or sysfs attributes can be specified.
993 The entries in /dev/.udev/queue and /dev/.udev/failed have changed to
994 zero-sized files to avoid pointing to /sys and confuse broken tools which
995 scan the /dev directory. To retry failed events, udevtrigger --retry-failed
998 The rules and scripts to create udev rules for persistent network
999 devices and optical drives are in the extras/rules_generator directory
1000 now. If you use something similar, please consider replacing your own
1001 version with this, to share the support effort. The rule_generator
1002 installs its own rules into /etc/udev/rules.d.
1004 The cdrom_id tool installs its own rule now in /etc/udev/rules.d, cause
1005 the rule_generator depends on cdrom_id to be called in an earlier rule.
1011 Renaming of some key names (the old names still work):
1012 BUS -> SUBSYSTEMS, ID -> KERNELS, SYSFS -> ATTRS, DRIVER -> DRIVERS.
1013 (The behavior of the key DRIVER will change soon in one of the next
1014 releases, to match only the event device, please switch to DRIVERS
1015 instead. If DRIVER is used, it will behave like DRIVERS, but an error
1017 With the new key names, we have a more consistent and simpler scheme.
1018 We can match the properties of the event device only, with: KERNEL,
1019 SUBSYSTEM, ATTR, DRIVER. Or include all the parent devices in the match,
1020 with: KERNELS, SUBSYSTEMS, ATTRS, DRIVERS. ID, BUS, SYSFS, DRIVER are no
1021 longer mentioned in the man page and should be switched in the rule
1024 ATTR{file}="value" can be used now, to write to a sysfs file of the
1025 event device. Instead of:
1026 ..., SYSFS{type}=="0|7|14", RUN+="/bin/sh -c 'echo 60 > /sys$$DEVPATH/timeout'"
1028 ..., ATTR{type}=="0|7|14", ATTR{timeout}="60"
1030 All the PHYSDEV* keys are deprecated and will be removed from a
1032 PHYDEVPATH - is the path of a parent device and should not be
1034 PHYSDEVBUS - is just a SUBSYSTEM value of a parent, and can be
1035 matched with SUBSYSTEMS==
1036 PHYSDEVDRIVER - for bus devices it is available as ENV{DRIVER}.
1037 Newer kernels will have DRIVER in the environment,
1038 for older kernels udev puts in. Class device will
1039 no longer carry this property of a parent and
1040 DRIVERS== can be used to match such a parent value.
1041 Note that ENV{DRIVER} is only available for a few bus devices, where
1042 the driver is already bound at device event time. On coldplug, the
1043 events for a lot devices are already bound to a driver, and they will have
1044 that value set. But on hotplug, at the time the kernel creates the device,
1045 it can't know what driver may claim the device after that, therefore
1046 in most cases it will be empty.
1048 Failed events should now be re-triggered with:
1049 udevtrigger --retry-failed.
1050 Please switch to this command, so we keep the details of the /dev/.udev/failed/
1051 files private to the udev tools. We may need to switch the current symlink
1052 target, cause some obviously broken tools try to scan all files in /dev
1053 including /dev/.udev/, find the links to /sys and end up stat()'ing sysfs files
1054 million times. This takes ages on slow boxes.
1056 The udevinfo attribute walk (-a) now works with giving a device node
1057 name (-n) instead of a devpath (-p). The query now always works, also when
1058 no database file was created by udev.
1060 The built-in /etc/passwd /etc/group parser is removed, we always depend on
1061 getpwnam() and getgrnam() now. One of the next releases will depend on
1062 fnmatch() and may use getopt_long().
1066 Bugfixes and small improvements.
1070 Fix path_id for recent kernels.
1076 Added support for swapping network interface names, by temporarily
1077 renaming the device and wait for the target name to become free.
1081 The built-in MODALIAS key and substitution is removed.
1085 The binary firmware helper is replaced by the usual simple
1086 shell script. Udevsend is removed from the tree.
1094 Some more keys require the correct use of '==' and '=' depending
1095 on the kind of operation beeing an assignment or a match. Rules
1096 with invalid operations are skipped and logged to syslog. Please
1097 test with udevtest if the parsing of your rules throws errors and
1098 fix possibly broken rules.
1102 Provide "udevsettle" to wait for all current udev events to finish.
1103 It also watches the current kernel netlink queue by comparing the
1104 even sequence number to make sure that there are no current pending
1105 events that have not already arrived in the daemon.
1109 Fix rule to skip persistent rules for removable IDE devices, which
1110 also skipped optical IDE drives.
1112 All *_id program are installed in /lib/udev/ by default now.
1114 No binary is stripped anymore as this should be done in the
1115 packaging process and not at build time.
1117 libvolume_id is provided as a shared library now and vol_id is
1118 linked against it. Also one of the next HAL versions will require
1119 this library, and the HAL build process will also require the
1120 header file to be installed. The copy of the same code in HAL will
1121 be removed to have only a single copy left on the system.
1125 Add persistent links for SCSI tapes. The rules file is renamed
1126 to 60-persistent-storage.rules.
1128 Create persistent path for usb devices. Can be used for all sorts
1129 of devices that can't be distinguished by other properties like
1130 multiple identical keyboards and mice connected to the same box.
1132 Provide "udevtrigger" program to request events on coldplug. The
1133 shell script is much too slow with thousends of devices.
1137 Fix persistent disk rules to exclude removable IDE drives.
1139 Warn if %e, $modalias or MODALIAS is used.
1143 Fix queue export, which wasn't correct for subsequent add/remove
1144 events for the same device.
1148 Fix cramfs detection on big endian.
1150 Make WAIT_FOR_SYSFS usable in "normal" rules and silent if the whole
1155 If BUS== and SYSFS{}== have been used in the same rule, the sysfs
1156 attributes were only checked at the parent device that matched the
1157 by BUS requested subsystem. Fix it to also look at the device we
1158 received the event for.
1160 Build variable CROSS has changed to CROSS_COMPILE to match the kernel
1165 Fix a bug where NAME="" would prevent RUN from beeing executed.
1167 RUN="/bin/program" does not longer automatically add the subsystem
1168 as the first parameter. This is from the days of /sbin/hotplug
1169 which is dead now and it's just confusing to need to add a space at
1170 the end of the program name to prevent this.
1171 If you use rules that need the subsystem as the first parameter,
1172 like the old "udev_run_hotlugd" and "udev_run_devd", add the subsystem
1173 to the key like RUN+="/bin/program $env{SUBSYSTEM}".
1177 The udev man page has moved to udev(7) as it does not describe a command
1178 anymore. The programs udev, udevstart and udevsend are no longer installed
1179 by default and must be copied manually, if they should be installed or
1180 included in a package.
1182 Fix a bug where "ignore_device" could run earlier collected RUN keys before
1183 the ignore rule was applied.
1185 More preparation for future sysfs changes. usb_id and scsi_id no longer
1186 depend on a magic order of devices in the /devices chain. Specific devices
1187 should be requested by their subsytem.
1189 This will always find the scsi parent device without depending on a specific
1191 dev = sysfs_device_get(devpath);
1192 dev_usb = sysfs_device_get_parent_with_subsystem(dev, "scsi");
1194 The "device" link in the current sysfs layout will be automatically
1195 _resolved_ as a parent and in the new sysfs layout it will just _be_ the
1196 parent in the devpath. If a device is requested by it's symlink, like all
1197 class devices in the new sysfs layout will look like, it gets automatically
1198 resolved and substituted with the real devpath and not the symlink path.
1201 A similar logic must be applied to _all_ sysfs users, including
1202 scripts, that search along parent devices in sysfs. The explicit use of
1203 the "device" link must be avoided. With the future sysfs layout all
1204 DEVPATH's will start with /devices/ and have a "subsystem" symlink poiting
1205 back to the "class" or the "bus". The layout of the parent devices in
1206 /devices is not necessarily expected to be stable across kernel releases and
1207 searching for parents by their subsystem should make sysfs users tolerant
1208 for changed parent chains.
1212 Prepare udev to work with the experimental kernel patch, that moves
1213 /sys/class devices to /sys/devices and /sys/block to /sys/class/block.
1215 Clarify BUS, ID, $id usage and fix $id behavior. This prepares for
1216 moving the class devices to /sys/devices.
1218 Thanks again to Marco for help finding a hopefully nice compromise
1219 to make %b simpler and working again.
1223 Complete removal of libsysfs, replaced by simple helper functions
1224 which are much simpler and a bit faster. The udev daemon operatesentirely
1225 on event parameters and does not use sysfs for simple rules anymore.
1226 Please report any new bugs/problems, that may be caused by this big
1227 change. They will be fixed immediately.
1229 The enumeration format character '%e' is deprecated and will be
1230 removed sometimes from a future udev version. It never worked correctly
1231 outside of udevstart, so we can't use it with the new parallel
1232 coldplug. A simple enumeration is as useless as the devfs naming
1233 scheme, just get rid of both if you still use it.
1235 MODALIAS and $modalias is not needed and will be removed from one of
1236 the next udev versions, replace it in all rules with ENV{MODALIAS} or
1237 the sysfs "modalias" value.
1239 Thanks a lot to Marco for all his help on finding and fixing bugs.
1243 Let scsi_id request libata drive serial numbers from page 0x80.
1245 Renamed etc/udev/persistent.rules to persistent-disk.rules and
1246 added /dev/disk/by-name/* for device mapper device names.
1248 Removed %e from the man page. It never worked reliably outside
1249 of udevstart and udevstart is no longer recommended to use.
1253 Symlinks are now exported to the event environment. Hopefully it's no
1254 longer needed to run udevinfo from an event process, like it was
1255 mentioned on the hotplug list:
1256 UDEV [1134776873.702967] add@/block/sdb
1259 DEVLINKS=/dev/disk/by-id/usb-IBM_Memory_Key_0218B301030027E8 /dev/disk/by-path/usb-0218B301030027E8:0:0:0
1263 Fix a problem if udevsend is used as the hotplug handler and tries to use
1264 syslog, which causes a "vc" event loop. 2.6.15 will make udevsend obsolete
1265 and this kind of problems will hopefully go away soon.
1269 All built-in logic to work around bad sysfs timing is removed with this
1270 version. The need to wait for sysfs files is almost fixed with a kernel
1271 version that doesn't work with this udev version anyway. Until we fix
1272 the timing of the "bus" link creation, the former integrated logic should
1273 be emulated by a rule placed before all other rules:
1274 ACTION=="add", DEVPATH=="/devices/*", ENV{PHYSDEVBUS}=="?*", WAIT_FOR_SYSFS="bus"
1276 The option "udev_db" does no longer exist. All udev state will be in
1277 /$udev_root/.udev/ now, there is no longer an option to set this
1279 If the init script or something else used this value, just depend on
1280 this hardcoded path. But remember _all_content_ of this directory is
1281 still private to udev and can change at any time.
1283 Default location for rule sripts and helper programs is now: /lib/udev/.
1284 Everything that is not useful on the commandline should go into this
1285 directory. Some of the helpers in the extras folder are installed there
1286 now. The rules need to be changed, to find the helpers there.
1288 Also /lib/udev/devices is recommended as a directory where packages or
1289 the user can place real device nodes, which get copied over to /dev at
1290 every boot. This should replace the various solutions with custom config
1293 Udevsend does no longer start the udev daemon. This must be done with
1294 the init script that prepares /dev on tmpfs and creates the initial nodes,
1295 before starting the daemon.
1299 Silent a too verbose error logging for the old hotplug.d/ dev.d/
1302 The copy of klibc is removed. A systemwide installed version of klibc
1303 should be used to build a klibc udev now.
1307 NAME="" will not create any nodes, but execute RUN keys. To completely
1308 ignore an event the OPTION "ignore_device" should be used.
1310 After removal of the reorder queue, events with a TIMEOUT can be executed
1311 without any queuing now.
1315 Fixed bug in udevd, if inotify is not available. We depend on netlink
1316 uevents now, kernels without that event source will not work with that
1317 version of udev anymore.
1321 The rule parsing happens now in the daemon once at startup, all udev
1322 event processes inherit the already parsed rules from the daemon.
1323 It is shipped with SUSE10.0 and reduces heavily the system load at
1324 startup. The option to save precompiled rules and let the udev process
1325 pick the them up is removed, as it's no longer needed.
1327 Kernel 2.6.15 will have symlinks at /class/input pointing to the real
1328 device. Libsysfs is changed to "translate" the requested link into the
1329 real device path, as it would happen with the hotplug event. Otherwise
1330 device removal and the udev database will not work.
1332 Using 'make STRIPCMD=' will leave the binaries unstripped for debugging
1335 A few improvements for vol_id, the filesytem probing code.
1339 Fix a stupid typo in extras/run_directory for "make install".
1341 scsi_id creates the temporary devnode now in /dev for usage with a
1342 non-writable /tmp directory.
1344 The uevent kernel socket buffer can carry app. 50.000 events now,
1345 let's see who can break this again. :)
1347 The upcoming kernel will have a new input driver core integration.
1348 Some class devices are now symlinks to the real device. libsysfs
1349 needs a fix for this to work correctly. Udevstart of older udev
1350 versions will _not_ create these devices!
1354 Fix a 'install' target in the Makefile, that prevents EXTRAS from
1359 A bunch of mostly trivial bugfixes. From now on no node name or
1360 symlink name can contain any character than plain whitelisted ascii
1361 characters or validated utf8 byte-streams. This is needed for the
1362 /dev/disk/by-label/* links, because we import untrusted data and
1363 export it to the filesystem.
1367 More bugfixes. If udevd was started from the kernel, we don't
1368 have stdin/stdout/stderr, which broke the forked tools in some
1373 Bugfix. udevstart event ordering was broken for a long time.
1374 The new run_program() uncovered it, because /dev/null was not
1375 available while we try to run external programs.
1376 Now udevstart should create it before we run anything.
1380 Minor bugfixes and some distro rules updates. If you don't have the
1381 persistent disk rules in /dev/disk/by-*/* on your distro, just
1382 grab it from here. :)
1386 We can use socket communication now to pass events from udev to
1388 RUN+="socket:/org/freedesktop/hal/udev_event"
1389 will pass the whole udev event to the HAL daemon without the need
1390 for a forked helper. (See ChangeLog for udevmonitor, as an example)
1394 Mostly bugfixes and see ChangeLog.
1396 The test for the existence of an environment value should be
1398 ENV{KEY}=="*" to ENV{KEY}=="?*"
1399 because "*" will not fail anymore, if the key does not exist or
1404 Bugfixes and a few tweaks described in the ChangeLog.
1408 Mostly a Bugfix release.
1410 Added WAIT_FOR_SYSFS="<attribute>" to be able to fight against the sysfs
1411 timing with custom rules.
1415 We changed the internal rule storage format. Our large rule files took
1416 2 MB of RAM, with the change we are down to 99kB.
1418 If the device-node has been created with default name and no symlink or
1419 options are to remenber, it is not longer stored in the udevdb. HAL will
1420 need to be updated to work correctly with that change.
1422 To overrride optimization flags, OPTFLAGS may be used now.
1430 Major changes happened with this release. The goal is to take over the
1431 complete kernel-event handling and provide a more efficient way to dispatch
1432 kernel events. Replacing most of the current shell script logic and the
1433 kernel forked helper with a netlink-daemon and a rule-based event handling.
1435 o udevd listens to netlink events now. The first valid netlink event
1436 will make udevd ignore any message from udevsend that contains a
1437 SEQNUM, to avoid duplicate events. The forked events can be disabled
1439 echo "" > /proc/sys/kernel/hotplug
1440 For full support, the broken input-subsytem needs to be fixed, not to
1441 bypass the driver core.
1443 o /etc/dev.d/ + /etc/hotplug.d/ directory multiplexing is completely
1444 removed from udev itself and must be emulated by calling small
1445 helper binaries provided in the extras folder:
1446 make EXTRAS=extras/run_directory/
1447 will build udev_run_devd and udev_run_hotplugd, which can be called
1448 from a rule if needed:
1449 RUN+="/sbin/udev_run_hotplugd"
1450 The recommended way to handle this is to convert all the calls from
1451 the directories to explicit udev rules and get completely rid of the
1452 multiplexing. (To catch a ttyUSB event, you now no longer need to
1453 fork and exit 300 tty script instances you are not interested in, it
1454 is just one rule that matches exactly the device.)
1456 o udev handles now _all_ events not just events for class and block
1457 devices, this way it is possible to control the complete event
1458 behavior with udev rules. Especially useful for rules like:
1459 ACTION="add", DEVPATH="/devices/*", MODALIAS=="?*", RUN+="/sbin/modprobe $modalias"
1461 o As used in the modalias rule, udev supports now textual
1462 substitution placeholder along with the usual format chars. This
1463 needs to be documented, for now it's only visible in udev_rules_parse.c.
1465 o The rule keys support now more operations. This is documented in the
1466 man page. It is possible to add values to list-keys like the SYMLINK
1467 and RUN list with KEY+="value" and to clear the list by assigning KEY="".
1468 Also "final"-assignments are supported by using KEY:="value", which will
1469 prevent changing the key by any later rule.
1471 o kernel 2.6.12 has the "detached_state" attribute removed from
1472 sysfs, which was used to recognize sysfs population. We switched that
1473 to wait for the "bus" link, which is only available in kernels after 2.6.11.
1474 Running this udev version on older kernels may cause a short delay for
1477 o To provide infrastructure for persistent device naming, the id programs:
1478 scsi_id, vol_id (former udev_volume_id), and ata_id (new) are able now
1479 to export the probed data in environment key format:
1480 pim:~ # /sbin/ata_id --export /dev/hda
1481 ID_MODEL=HTS726060M9AT00
1482 ID_SERIAL=MRH401M4G6UM9B
1483 ID_REVISION=MH4OA6BA
1485 The following rules:
1486 KERNEL="hd*[!0-9]", IMPORT="/sbin/ata_id --export $tempnode"
1487 KERNEL="hd*[!0-9]", ENV{ID_SERIAL}=="?*", SYMLINK+="disk/by-id/$env{ID_MODEL}_$env{ID_SERIAL}"
1490 kay@pim:~> tree /dev/disk
1493 | |-- HTS726060M9AT00_MRH401M4G6UM9B -> ../../hda
1494 | `-- IBM-Memory_Key -> ../../sda
1496 | |-- swap -> ../../hda1
1497 | |-- date -> ../../sda1
1498 | `-- home -> ../../hda3
1500 |-- 2E08712B0870F2E7 -> ../../hda3
1501 |-- 9352cfef-7687-47bc-a2a3-34cf136f72e1 -> ../../hda1
1502 |-- E845-7A89 -> ../../sda1
1503 `-- b2a61681-3812-4f13-a4ff-920d70604299 -> ../../hda2
1505 The IMPORT= operation will import these keys in the environment and make
1506 it available for later PROGRAM= and RUN= executed programs. The keys are
1507 also stored in the udevdb and can be queried from there with one of the
1510 o A few binaries are silently added to the repository, which can be used
1511 to replay kernel events from initramfs instead of using coldplug. udevd
1512 can be instructed now to queue-up events while the stored events from
1513 initramfs are filled into the udevd-queue. This code is still under
1514 development and there is no documentation now besides the code itself.
1515 The additional binaries get compiled, but are not installed by default.
1517 o There is also a temporary fix for a performance problem where too many
1518 events happen in parallel and every event needs to parse the rules.
1519 udev can now read precompiled rules stored on disk. This is likely to be
1520 replaced by a more elegant solution in a future udev version.
1524 With kernel version 2.6.12, the sysfs file "detached_state" was removed.
1525 Fix for libsysfs not to expect this file was added.
1529 All rules are applied now, but only the first matching rule with a NAME-key
1530 will be applied. All later rules with NAME-key are completely ignored. This
1531 way system supplied symlinks or permissions gets applied to user-defined
1535 Please check your rules setup, if you may need to add OPTIONS="last_rule"
1536 to some rules, to keep the old behavior.
1538 The rules are read on "remove"-events too. That makes is possible to match
1539 with keys that are available on remove (KERNEL, SUBSYSTEM, ID, ENV, ...) to
1540 instruct udev to ignore an event (OPTIONS="ignore_device").
1541 The new ACTION-key may be used to let a rule act only at a "remove"-event.
1543 The new RUN-key supports rule-based execution of programs after device-node
1544 handling. This is meant as a general replacement for the dev.d/-directories
1545 to give fine grained control over the execution of programs.
1547 The %s{}-sysfs format char replacement values are searched at any of the
1548 devices in the device chain now, not only at the class-device.
1550 We support log priority levels now. The value udev_log in udev.conf is used
1551 to determine what is printed to syslog. This makes it possible to
1552 run a version with compiled-in debug messages in a production environment
1553 which is sometimes needed to find a bug.
1554 It is still possible to supress the inclusion of _any_ syslog usage with
1555 USE_LOG=false to create the smallest possible binaries if needed.
1556 The configured udev_log value can be overridden with the environment variable
1561 Possible use of a system-wide klibc:
1562 make USE_KLIBC=true KLCC=/usr/bin/klcc all
1563 will link against an external klibc and our own version will be ignored.
1567 We support an unlimited count of symlinks now.
1569 If USE_STATIC=true is passed to a glibc build, we link statically and use
1570 a built-in userdb parser to resolve user and group names.
1572 The PLACE= key is gone. It can be replaced by an ID= for a long time, because
1573 we walk up the chain of physical devices to find a match.
1575 The KEY="<value>" format supports '=', '==', '!=,' , '+=' now. This makes it
1576 easy to skip certain attribute matches without composing rules with weird
1577 character class negations like:
1578 KERNEL="[!s][!c][!d]*"
1579 this can now be replaced with:
1581 The current simple '=' is still supported, and should work as it does today,
1582 but existing rules should be converted if possible, to be better readable.
1584 We have new ENV{}== key now, to match against a maximum of 5 environment
1587 udevstart is its own binary again, because we don't need co carry this araound
1588 with every forked event.