5 Udev now enables kernel media-presence polling if available. Part
6 of udisks optical drive tray-handling moved to cdrom_id: The tray
7 is locked as soon as a media is detected to enable the receiving
8 of media-eject-request events. Media-eject-request events will
11 Libudev enumerate is now able to enumerate a subtree of a given
14 The mobile-action-modeswitch modeswitch tool was deleted. The
15 functionality is provided by usb_modeswitch now.
21 The systemd service files require systemd version 28. The systemd
22 socket activation make it possible now to start 'udevd' and 'udevadm
27 Fix bug in control message handling, which can lead to a failing
28 udevadm control --exit. Thanks to Jürg Billeter for help tracking
35 We require at least Linux kernel 2.6.32 now. Some platforms might
36 require a later kernel that supports accept4() and similar, or
37 need to backport the trivial syscall wiring to the older kernels.
39 The hid2hci tool moved to the bluez package and was removed.
41 Many of the extras can be --enable/--disabled at ./configure
42 time. The --disable-extras option was removed. Some extras have
43 been disabled by default. The current options and their defaults
44 can be checked with './configure --help'.
50 Udev logs a warning now if /run is not writable at udevd
51 startup. It will still fall back to /dev/.udev, but this is
54 The running udev daemon can now cleanly shut down with:
55 udevadm control --exit
57 Udev in initramfs should clean the state of the udev database
58 with: udevadm info --cleanup-db which will remove all state left
59 behind from events/rules in initramfs. If initramfs uses
60 --cleanup-db and device-mapper/LVM, the rules in initramfs need
61 to add OPTIONS+="db_persist" for all dm devices. This will
62 prevent removal of the udev database for these devices.
64 Spawned programs by PROGRAM/IMPORT/RUN now have a hard timeout of
65 120 seconds per process. If that timeout is reached the spawned
66 process will be killed. The event timeout can be overwritten with
69 If systemd is used, udev gets now activated by netlink data.
70 Systemd will bind the netlink socket which will buffer all data.
71 If needed, such setup allows a seemless update of the udev daemon,
72 where no event can be lost during a udevd update/restart.
73 Packages need to make sure to: systemctl stop udev.socket udev.service
74 or 'mask' udev.service during the upgrade to prevent any unwanted
75 auto-spawning of udevd.
76 This version of udev conflicts with systemd version below 25. The
77 unchanged service files will not wirk correctly.
83 The udev runtime data moved from /dev/.udev/ to /run/udev/. The
84 /run mountpoint is supposed to be a tmpfs mounted during early boot,
85 available and writable to for all tools at any time during bootup,
86 it replaces /var/run/, which should become a symlink some day.
88 If /run does not exist, or is not writable, udev will fall back using
91 On systemd systems with initramfs and LVM used, packagers must
92 make sure, that the systemd and initramfs versions match. The initramfs
93 needs to create the /run mountpoint for udev to store the data, and
94 mount this tmpfs to /run in the rootfs, so the that the udev database
95 is preserved for the udev version started in the rootfs.
97 The command 'udevadm info --convert-db' is gone. The udev daemon
98 itself, at startup, converts any old database version if necessary.
100 The systemd services files have been reorganized. The udev control
101 socket is bound by systemd and passed to the started udev daemon.
102 The udev-settle.service is no longer active by default. Services which
103 can not handle hotplug setups properly need to actively pull it in, to
104 act like a barrier. Alternatively the settle service can be unconditionally
105 'systemctl'enabled, and act like a barrier for basic.target.
107 The fstab_import callout is no longer built or installed. Udev
108 should not be used to mount, does not watch changes to fstab, and
109 should not mirror fstab values in the udev database.
115 New and updated keymaps.
121 The udev database has changed, After installation of a new udev
122 version, 'udevadm info --convert-db' should be called, to let the new
123 udev/libudev version read the already stored data.
125 udevadm now supports quoting of property values, and prefixing of
127 $ udevadm info --export --export-prefix=MY_ --query=property -n sda
130 MY_DEVNAME='/dev/sda'
134 libudev now supports:
135 udev_device_get_is_initialized()
136 udev_enumerate_add_match_is_initialized()
137 to be able to skip devices the kernel has created , but udev has
140 libudev now supports:
141 udev_device_get_usec_since_initialized()
142 to retrieve the "age" of a udev device record.
144 GUdev supports a more generic GUdevEnumerator class, udev TAG
145 handling, device initialization and timestamp now.
147 The counterpart of /sys/dev/{char,block}/$major:$minor,
148 /dev/{char,block}/$major:$minor symlinks are now unconditionally
149 created, even when no rule files exist.
151 New and updated keymaps.
157 GUdev moved from /usr to /.
167 Persistent network naming rules are disabled inside of Qemu/KVM now.
169 New and updated keymaps.
171 Udev gets unconditionally enabled on systemd installations now. There
172 is no longer the need to to run 'systemctl enable udev.service'.
186 New and fixed keymaps.
188 Install systemd service files if applicable.
194 All distribution specific rules are removed from the udev source tree,
195 most of them are no longer needed. The Gentoo rules which allow to support
196 older kernel versions, which are not covered by the default rules anymore
197 has moved to rules/misc/30-kernel-compat.rules.
203 The option --debug-trace and the environemnt variable UDEVD_MAX_CHILDS=
204 was removed from udevd.
206 Udevd now checks the kernel commandline for the following variables:
207 udev.log-priority=<syslog priority>
208 udev.children-max=<maximum number of workers>
209 udev.exec-delay=<seconds to delay the execution of RUN=>
210 to help debuging coldplug setups where the loading of a kernel
211 module crashes the system.
213 The subdirectory in the source tree rules/packages has been renamed to
214 rules/arch, anc contains only architecture specific rules now.
224 Now the udev daemon itself, does on startup:
225 - copy the content of /lib/udev/devices to /dev
226 - create the standard symlinks like /dev/std{in,out,err},
227 /dev/core, /dev/fd, ...
228 - use static node information provided by kernel modules
229 and creates these nodes to allow module on-demand loading
230 - possibly apply permissions to all ststic nodes from udev
231 rules which are annotated to match a static node
233 The default mode for a device node is 0600 now to match the kernel
234 created devtmpfs defaults. If GROUP= is specified and no MODE= is
235 given the default will be 0660.
241 Udev now gradually starts to pass control over the primary device nodes
242 and their names to the kernel, and will in the end only manage the
243 permissions of the node, and possibly create additional symlinks.
244 As a first step NAME="" will be ignored, and NAME= setings with names
245 other than the kernel provided name will result in a logged warning.
246 Kernels that don't provide device names, or devtmpfs is not used, will
247 still work as they did before, but it is strongly recommended to use
248 only the same names for the primary device node as the recent kernel
249 provides for all devices.
253 Fix broken firmware loader search path.
259 "udevadm trigger" defaults to "change" events now instead of "add"
260 events. The "udev boot script" might need to add "--action=add" to
261 the trigger command if not already there, in case the initial coldplug
262 events are expected as "add" events.
264 The option "all_partitons" was removed from udev. This should not be
265 needed for usual hardware. Udev can not safely make assumptions
266 about non-existing partition major/minor numbers, and therefore no
267 longer provide this unreliable and unsafe option.
269 The option "ignore_remove" was removed from udev. With devtmpfs
270 udev passed control over device nodes to the kernel. This option
271 should not be needed, or can not work as advertised. Neither
272 udev nor the kernel will remove device nodes which are copied from
273 the /lib/udev/devices/ directory.
275 All "add|change" matches are replaced by "!remove" in the rules and
276 in the udev logic. All types of events will update possible symlinks
277 and permissions, only "remove" is handled special now.
279 The modem modeswitch extra was removed and the external usb_modeswitch
280 program should be used instead.
282 New and fixed keymaps.
292 Kernels with SYSFS_DEPRECATED=y are not supported since a while. Many users
293 depend on the current sysfs layout and the information not available in the
294 deprecated layout. All remaining support for the deprecated sysfs layout is
299 Fix for a possible endless loop in the new input_id program.
305 The option "ignore_device" does no longer exist. There is no way to
306 ignore an event, as libudev events can not be suppressed by rules.
307 It only prevented RUN keys from being executed, which results in an
308 inconsistent behavior in current setups.
310 BUS=, SYSFS{}=, ID= are long deprecated and should be SUBSYSTEM(S)=,
311 ATTR(S){}=, KERNEL(S)=. It will cause a warning once for every rule
314 The support for the deprecated IDE devices has been removed from the
315 default set of rules. Distros who still care about non-libata drivers
316 need to add the rules to the compat rules file.
318 The ID_CLASS property on input devices has been replaced by the more accurate
319 set of flags ID_INPUT_{KEYBOARD,KEY,MOUSE,TOUCHPAD,TABLET,JOYSTICK}. These are
320 determined by the new "input_id" prober now. Some devices, such as touchpads,
321 can have several classes. So if you previously had custom udev rules which e. g.
322 checked for ENV{ID_CLASS}=="kbd", you need to replace this with
323 ENV{ID_INPUT_KEYBOARD}=="?*".
329 To support DEVPATH strings larger than the maximum file name length, the
330 private udev database format has changed. If some software still reads the
331 private files in /dev/.udev/, which it shouldn't, now it's time to fix it.
332 Please do not port anything to the new format again, everything in /dev/.udev
333 is and always was private to udev, and may and will change any time without
336 Multiple devices claiming the same names in /dev are limited to symlinks
337 only now. Mixing identical symlink names and node names is not supported.
338 This reduces the amount of data in the database significantly.
340 NAME="%k" causes a warning now. It's is and always was completely superfluous.
341 It will break kernel supplied DEVNAMEs and therefore it needs to be removed
344 Most NAME= instructions got removed. Kernel 2.6.31 supplies the needed names
345 if they are not the default. To support older kernels, the NAME= rules need to
346 be added to the compat rules file.
348 Symlinks to udevadm with the old command names are no longer resolved to
349 the udevadm commands.
351 The udev-acl tool got adopted to changes in ConsoleKit. Version 0.4.1 is
354 The option "last_rule" does no longer exist. Its use breaks too many
355 things which expect to be run from independent later rules, and is an idication
356 that something needs to be fixed properly instead.
358 The gudev API is no longer marked as experimental,
359 G_UDEV_API_IS_SUBJECT_TO_CHANGE is no longer needed. The gudev introspection
360 is enabled by default now. Various projects already depend on introspection
361 information to bind dynamic languages to the gudev interfaces.
367 The udevadm trigger "--retry-failed" option, which is replaced since quite
368 a while by "--type=failed" is removed.
370 The failed tracking was not working at all for a few releases. The RUN
371 option "ignore_error" is replaced by a "fail_event_on_error" option, and the
372 default is not to track any failing RUN executions.
374 New keymaps, new modem, hid2hci updated.
378 Fix possible crash in udevd when worker processes are busy, rules are
379 changed at the same time, and workers get killed to reload the rules.
385 Properties set with ENV{.FOO}="bar" are marked private by starting the
386 name with a '.'. They will not be stored in the database, and not be
387 exported with the event.
389 Firmware files are looked up in:
390 /lib/firmware/updates/$(uname -r)
391 /lib/firmware/updates
392 /lib/firmware/$(uname -r)
396 ATA devices switched the property from ID_BUS=scsi to ID_BUS=ata.
397 ata_id, instead of scsi_id, is the default tool now for ATA devices.
403 The configure options have changed because another library needs to be
404 installed in a different location. Instead of exec_prefix and udev_prefix,
405 libdir, rootlibdir and libexecdir are used. The Details are explained in
408 Event processes now get re-used after they handled an event. This reduces
409 the number of forks and the pressure on the CPU significantly, because
410 cloned event processes no longer cause page faults in the main daemon.
411 After the events have settled, a few worker processes stay around for
412 future events, all others get cleaned up.
414 To be able to use signalfd(), udev depends on kernel version 2.6.25 now.
415 Also inotify support is mandatory now to run udev.
417 The format of the queue exported by the udev damon has changed. There is
418 no longer a /dev/.udev/queue/ directory. The current event queue can be
419 accessed with udevadm settle and libudedv.
421 Libudev does not have the unstable API header anymore. From now on,
422 incompatible changes will be handled by bumping the library major version.
424 To build udev from the git tree gtk-doc is needed now. The tarballs will
425 build without it and contain the pre-built documentation. An online copy
427 http://www.kernel.org/pub/linux/utils/kernel/hotplug/libudev/
429 The tools from the udev-extras repository have been merged into the main
430 udev repository. Some of the extras have larger external dependencies, and
431 they can be disabled with the configure switch --disable-extras.
437 The program vol_id and the library libvolume_id are removed from the
438 repository. Libvolume_id is merged with libblkid from the util-linux-ng
439 package. Persistent disk links for label and uuid depend on the
440 util-linux-ng version (2.15) of blkid now. Older versions of blkid
441 can not be used with udev.
443 Libudev allows to subscribe to udev events. To prevent unwanted messages
444 to be delivered, and waking up the subscribing process, a filter can be
445 installed, to drop messages inside a kernel socket filter. The filters
446 match on the <subsytem>:<devtype> properties of the device.
447 This is part of the ongoing effort to replace HAL, and switch current
448 users over to directly use libudev.
449 Libudev is still marked as experimental, and its interface might
450 eventually change if needed, but no major changes of the currently exported
451 interface are expected anymore, and a first stable release should happen
454 A too old kernel (2.6.21) or a kernel with CONFIG_SYSFS_DEPRECATED
455 is not supported since while and udevd will log an error message at
456 startup. It should still be able to boot-up, but advanced rules and system
457 services which depend on the information not available in the old sysfs
458 format will fail to work correctly.
460 DVB device naming is supplied by the kernel now. In case older kernels
461 need to be supported, the old shell script should be added to a compat
468 The processed udev events get send back to the netlink socket. Libudev
469 provides access to these events. This is work-in-progress, to replace
470 the DeviceKit daemon functionality directly with libudev. There are
471 upcoming kernel changes to allow non-root users to subcribe to these
478 "udevadm settle" now optionally accepts a range of events to wait for,
479 instead of waiting for "all" events.
485 The installed watch for block device metadata changes is now removed
486 during event hadling, because some (broken) tools may be called from udev
487 rules and (wrongly) open the device with write access. After the finished
488 event handling the watch is restored.
494 Device nodes can be watched for changes with inotify with OPTIONS="watch".
495 If closed after being opened for writing, a "change" uevent will occur.
496 /dev/disk/by-{label,uuid}/* symlinks will be automatically updated.
502 The udevadm test command has no longer a --force option, nodes and symlinks
503 are always updated with a test run now.
505 The udevd daemon can be started with --resolve-names=never to avoid all user
506 and group lookups (e.g. in cut-down systems) or --resolve-names=late to
507 lookup user and groups every time events are handled.
513 We are currently merging the Ubuntu rules in the udev default rules,
514 and get one step closer to provide a common Linux /dev setup, regarding
515 device names, symlinks, and default device permissions. On udev startup,
516 we now expect the following groups to be resolvable to their ids with
518 disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem.
519 LDAP setups need to make sure, that these groups are always resolvable at
520 bootup, with only the rootfs mounted, and without network access available.
522 Some systems may need to add some new, currently not used groups, or need
523 to add some users to new groups, but the cost of this change is minimal,
524 compared to the pain the current, rather random, differences between the
525 various distributions cause for upstream projects and third-party vendors.
527 In general, "normal" users who log into a machine should never be a member
528 of any such group, but the device-access should be managed by dynamic ACLs,
529 which get added and removed for the specific users on login/logout and
530 session activity/inactivity. These groups are only provided for custom setups,
531 and mainly system services, to allow proper privilege separation.
532 A video-streaming daemon uid would be a member of "audio" and "video", to get
533 access to the sound and video devices, but no "normal" user should ever belong
534 to the "audio" group, because he could listen to the built-in microphone with
535 any ssh-session established from the other side of the world.
537 /dev/serial/by-{id,path}/ now contains links for ttyUSB devices,
538 which do not depend on the kernel device name. As usual, unique
539 devices - only a single one per product connected, or a real
540 USB serial number in the device - are always found with the same
541 name in the by-id/ directory.
542 Completely identical devices may overwrite their names in by-id/
543 and can only be found reliably in the by-path/ directory. Devices
544 specified by by-path/ must not change their connection, like the
545 USB port number they are plugged in, to keep their name.
547 To support some advanced features, Linux 2.6.22 is the oldest supported
548 version now. The kernel config with enabled SYSFS_DEPRECATED is no longer
549 supported. Older kernels should still work, and devices nodes should be
550 reliably created, but some rules and libudev will not work correctly because
551 the old kernels do not provide the expected information or interfaces.
557 Fix for a possible segfault while swapping network interface names in udev
564 The group "video" is part of the default rules now.
568 Bugfix for kernels using SYSFS_DEPRECATED* option and finding parent
569 block devices in some cases. No common distro uses this option anymore,
570 and we do not get enough testing for this and recent udev versions. If
571 this option is not needed to run some old distro with a new kernel,
572 it should be disabled in the kernel config.
574 Bugfix for the $links substitution variable, which may crash if no links
575 are created. This should not happen in usual setups because we always
576 create /dev/{block,char}/ links.
578 The strings of the parsed rules, which are kept in memory, no longer
579 contain duplicate entries, or duplicate tails of strings. This, and the
580 new rules parsing/matching code reduces the total in-memory size of
581 a huge distro rule sets to 0.08 MB, compared to the 1.2MB of udev
584 The export of DEVTYPE=disk/partition got removed from the default
585 rules. This value is available from the kernel. The pnp shell script
586 modprobe hack is removed from the default rules. ACPI devices have _proper_
587 modalias support and take care of the same functionality.
588 Installations which support old kernels, but install current default
589 udev rules may want to add that to the compat rules file.
591 Libvolume_id now always probes for all known filesystems, and does not
592 stop at the first match. Some filesystems are marked as "exclusive probe",
593 and if any other filesytem type matches at the same time, libvolume_id
594 will, by default, not return any probing result. This is intended to prevent
595 mis-detection with conflicting left-over signatures found from earlier
596 file system formats. That way, we no longer depend on the probe-order
597 in case of multiple competing signatures. In some setups the kernel allows
598 to mount a volume with just the old filesystem signature still in place.
599 This may damage the new filesystem and cause data-loss, just by mounting
600 it. Because volume_id can not decide which one the correct signature is,
601 the wrong signatures need to be removed manually from the volume, or the
602 volume needs to be reformatted, to enable filesystem detection and possible
607 Fix segfault if compiled without optimization and dbg() does not get
608 compiled out and uses variables which are not available.
612 Bugfixes. (And maybe new bugs. :))
614 The rule matching engine got converted from a rule list to a token
615 array which reduced the in-memory rules representation of a full
616 featured distros with thousends of udev rules from 1.2MB to 0.12 MB.
617 Limits like 5 ENV and ATTR matches, and one single instance for most
618 other keys per rule are gone.
620 The NAME assignment is no longer special cased. If later rules assign
621 a NAME value again, the former value will be overwritten. As usual
622 for most other keys, the NAME value can be protected by doing a final
623 assignment with NAME:="<value>".
625 All udev code now uses libudev, which is also exported. The library
626 is still under development, marked as experimental, and its interface
627 may change as long as the DeviceKit integration is not finished.
629 Many thanks to Alan Jenkins for his continuous help, and finding and
630 optimizing some of the computing expensive parts.
636 Kernel devices and device nodes are connected now by reverse indizes in
637 /sys and /dev. A device number retrieved by a stat() or similar, the
638 kernel device directory can be found by looking up:
639 /sys/dev/{block,char}/<maj>:<min>
640 and the device node of the same device by looking up:
641 /dev/{block,char}/<maj>:<min>
645 Fix recently introduced bug, which caused a compilation without large
646 file support, where vol_id does not recognize raid signatures at the end
649 Firewire disks now create both, by-id/scsi-* and by-id/ieee-* links.
650 Seems some kernel versions prevent the creation of the ieee-* links,
651 so people used the scsi-* link which disappeared now.
653 More libudev work. Almost all udevadm functionality comes from libudev
656 udevadm trigger has a new option --type, which allows to trigger events
657 for "devices", for "subsystems", or "failed" devices. The old option
658 --retry-failed" still works, but is no longer mentioned in the man page.
664 The udevadm info --device-id-of-file= output has changed to use
665 the obvious format. Possible current users should use the --export
666 option which is not affected.
668 The old udev commands symlinks to udevadm are not installed, if
669 these symlinks are used, a warning is printed.
675 Optical drive's media is no longer probed for raid signatures,
676 reading the end of the device causes some devices to malfunction.
677 Also the offset of the last session found is used now to probe
680 The volume_id library got a major version number update to 1,
681 some deprecated functions are removed.
683 A shared library "libudev" gets installed now to provide access
684 to udev device information. DeviceKit, the successor of HAL, will
685 need this library to access the udev database and search sysfs for
687 The library is currently in an experimental state, also the API is
688 expected to change, as long as the DeviceKit integration is not
693 We use ./configure now. See INSTALL for details. Current
696 "/usr" - prefix for man pages, include files
698 "" - the root filesystem, prefix for libs and binaries
702 "lib" - directory name for libraries, not a path name
703 multilib 64bit systems may use "lib64" instead of "lib"
705 compile-in verbose debug messages
707 disable all logging and compile-out all log strings
709 link against SELInux libraries, to set the expected context
712 In the default rules, the group "disk" gets permissions 0660 instead
713 of 0640. One small step closer to unify distro rules. Some day, all
714 distros hopefully end up with the same set of rules.
716 No symlinks to udevadm are installed anymore, if they are still needed,
717 they should be provided by the package.
723 Default udev rules, which are not supposed to be edited by the user, should
724 be placed in /lib/udev/rules.d/ now, to make it clear that they are private to
725 the udev package and will be replaced with an update. Udev will pick up rule
727 /lib/udev/rules.d/ - default installed rules
728 /etc/udev/rules.d/ - user rules + on-the-fly generated rules
729 /dev/.udev/rules.d/ - temporary non-persistent rules created after bootup
730 It does not matter in which directory a rule file lives, all files are sorted
733 To help creating /dev/root, we have now:
734 $ udevadm info --export --export-prefix="ROOT_" --device-id-of-file=/
737 In case the current --device-id-of-file is already used, please switch to
738 the --export format version, it saves the output parsing and the old
739 format will be changed to use ':' as a separator, like the format in the
744 Fix cdrom_id to properly recognize blank media.
750 Tape drive id-data is queried from /dev/bsg/* instead of the tape
751 nodes. This avoids rewinding tapes on open().
757 The symlinks udevcontrol and udevtrigger are no longer installed by
760 The scsi_id program does not depend on sysfs anymore. It can speak
761 SGv4 now, so /dev/bsg/* device nodes can be used, to query SCSI device
762 data, which should solve some old problems with tape devices, where
763 we better do not open all tape device nodes to identify the device.
769 The cdrom_id program is replaced by an advanced version, which can
770 detect most common device types, and also properties of the inserted
771 media. This is part of moving some basic functionality from HAL into
772 udev (and the kernel).
778 The last WAIT_FOR_SYSFS rule is removed from the default rules.
780 The symlinks to udevadm for the debugging tools: udevmonitor and
781 udevtest are no longer created.
783 The symlinks to the udevadm man page for the old tool names are
786 Abstract namespace sockets paths in RUN+="socket:@<path>" rules,
787 should be prefixed with '@' to indicate that the path is not a
798 Udevstart is removed from the tree, it did not get installed for
799 a long time now, and is long replaced by trigger and settle.
805 All udev tools are merged into a single binary called udevadm.
806 The old names of the tools are built-in commands in udevadm now.
807 Symlinks to udevadm, with the names of the old tools, provide
808 the same functionality as the standalone tools. There is also
809 only a single udevadm.8 man page left for all tools.
811 Tools like mkinitramfs should be checked, if they need to include
812 udevadm in the list of files.
822 The etc/udev/rules.d/ directory now contains a default set of basic
823 udev rules. This initial version is the result of a rules file merge
824 of Fedora and openSUSE. For these both distros only a few specific
825 rules are left in their own file, named after the distro. Rules which
826 are optionally installed, because they are only valid for a specific
827 architecture, or rules for subsystems which are not always used are
828 in etc/udev/packages/.
834 Dynamic rules can be created in /dev/.udev/rules.d/ to trigger
835 actions by dynamically created rules.
837 SYMLINK=="<value>" matches agains the entries in the list of
838 currently defined symlinks. The links are not created in the
839 filesystem at that point in time, but the values can be matched.
841 RUN{ignore_error}+="<program>" will ignore any exit code from the
842 program and not record as a failed event.
848 Final merge of patches/features from the Ubuntu package.
854 Control characters in filesystem label strings are no longer silenty
855 removed, but hex-encoded, to be able to uniquely identify the device
856 by its symlink in /dev/disk/by-label/.
857 If libvolume_id is used by mount(8), LABEL= will work as expected,
858 if slashes or other characters are used in the label string.
860 To test the existence of a file, TEST=="<file>" and TEST!="<file>"
861 can be specified now. The TEST key accepts an optional mode mask
862 TEST{0100}=="<is executable file>".
864 Scsi_id now supports a mode without expecting scsi-specific sysfs
865 entries to allow the extraction of cciss-device persistent properties.
871 In the future, we may see uuid's which are just simple character
872 strings (see the DDF Raid Specification). For that reason vol_id now
873 exports ID_FS_UUID_SAFE, just like ID_FS_LABEL_SAFE. For things like
874 the creation of symlinks, the *_SAFE values ensure, that no control
875 or whitespace characters are used in the filename.
877 Possible users of libvolume_id, please use the volume_id_get_* functions.
878 The public struct will go away in a future release of the library.
884 Removal of useless extras/eventrecorder.sh.
894 The directory multiplexer for dev.d/ and hotplug.d are finally removed
895 from the udev package.
901 Symlinks can have priorities now, the priority is assigned to the device
902 and specified with OPTIONS="link_priority=100". Devices with higher
903 priorities overwrite the symlinks of devices with lower priorities.
904 If the device that currently owns the link, goes away, the symlink
905 will be removed, and recreated, pointing to the next device with the
906 highest actual priority. This should make /dev/disk/by-{label,uuid,id}
907 more reliable, if multiple devices contain the same metadata and overwrite
910 The dasd_id program is removed from the udev tree, and dasdinfo, with the
911 needed rules, are part of the s390-tools now.
913 Please add KERNEL=="[0-9]*:[0-9]*" to the scsi wait-for-sysfs rule,
914 we may get the scsi sysfs mess fixed some day, and this will only catch
915 the devices we are looking for.
917 USB serial numbers for storage devices have the target:lun now appended,
918 to make it possibble to distinguish broken multi-lun devices with all
919 the same SCSI identifiers.
921 Note: The extra "run_directory" which searches and executes stuff in
922 /etc/hotplug.d/ and /etc/dev.d/ is long deprecated, and will be removed
923 with the next release. Make sure, that you don't use it anymore, or
924 provides your own implementation of that inefficient stuff.
925 We are tired of reports about a "slow udev", because these directories
926 contain stuff, that runs with _every_ event, instead of using rules,
927 that run programs only for the matching events.
937 DRIVER== will match only for devices that actually have a real
938 driver. DRIVERS== must be used, if parent devices should be
939 included in the match.
941 Libvolume_id's "linux_raid" detection needed another fix.
949 Add additional check to volume_id detection of via_raid, cause
950 some company decided to put a matching pattern all over the empty
951 storage area of their music players.
955 Fix path_id for SAS devices.
959 The udev daemon can be started with --debug-trace now, which will
960 execute all events serialized to get a chance to catch a possible
961 action that crashes the box.
963 A warning is logged, if PHYSDEV* keys, the "device" link, or a parent
964 device attribute like $attr{../file} is used, only WAIT_FOR_SYSFS rules
965 are excluded from the warning. Referencing parent attributes directly
966 may break when something in the kernel driver model changes. Udev will
967 just find the attribute by walking up the parent chain.
969 Udevtrigger now sorts the list of devices depending on the device
970 dependency, so a "usb" device is triggered after the parent "pci"
975 Revert persistent-storage ata-serial '_' '-' replacement.
981 Udevtrigger can now filter the list of devices to be triggered. Matches
982 for subsystems or sysfs attributes can be specified.
984 The entries in /dev/.udev/queue and /dev/.udev/failed have changed to
985 zero-sized files to avoid pointing to /sys and confuse broken tools which
986 scan the /dev directory. To retry failed events, udevtrigger --retry-failed
989 The rules and scripts to create udev rules for persistent network
990 devices and optical drives are in the extras/rules_generator directory
991 now. If you use something similar, please consider replacing your own
992 version with this, to share the support effort. The rule_generator
993 installs its own rules into /etc/udev/rules.d.
995 The cdrom_id tool installs its own rule now in /etc/udev/rules.d, cause
996 the rule_generator depends on cdrom_id to be called in an earlier rule.
1002 Renaming of some key names (the old names still work):
1003 BUS -> SUBSYSTEMS, ID -> KERNELS, SYSFS -> ATTRS, DRIVER -> DRIVERS.
1004 (The behavior of the key DRIVER will change soon in one of the next
1005 releases, to match only the event device, please switch to DRIVERS
1006 instead. If DRIVER is used, it will behave like DRIVERS, but an error
1008 With the new key names, we have a more consistent and simpler scheme.
1009 We can match the properties of the event device only, with: KERNEL,
1010 SUBSYSTEM, ATTR, DRIVER. Or include all the parent devices in the match,
1011 with: KERNELS, SUBSYSTEMS, ATTRS, DRIVERS. ID, BUS, SYSFS, DRIVER are no
1012 longer mentioned in the man page and should be switched in the rule
1015 ATTR{file}="value" can be used now, to write to a sysfs file of the
1016 event device. Instead of:
1017 ..., SYSFS{type}=="0|7|14", RUN+="/bin/sh -c 'echo 60 > /sys$$DEVPATH/timeout'"
1019 ..., ATTR{type}=="0|7|14", ATTR{timeout}="60"
1021 All the PHYSDEV* keys are deprecated and will be removed from a
1023 PHYDEVPATH - is the path of a parent device and should not be
1025 PHYSDEVBUS - is just a SUBSYSTEM value of a parent, and can be
1026 matched with SUBSYSTEMS==
1027 PHYSDEVDRIVER - for bus devices it is available as ENV{DRIVER}.
1028 Newer kernels will have DRIVER in the environment,
1029 for older kernels udev puts in. Class device will
1030 no longer carry this property of a parent and
1031 DRIVERS== can be used to match such a parent value.
1032 Note that ENV{DRIVER} is only available for a few bus devices, where
1033 the driver is already bound at device event time. On coldplug, the
1034 events for a lot devices are already bound to a driver, and they will have
1035 that value set. But on hotplug, at the time the kernel creates the device,
1036 it can't know what driver may claim the device after that, therefore
1037 in most cases it will be empty.
1039 Failed events should now be re-triggered with:
1040 udevtrigger --retry-failed.
1041 Please switch to this command, so we keep the details of the /dev/.udev/failed/
1042 files private to the udev tools. We may need to switch the current symlink
1043 target, cause some obviously broken tools try to scan all files in /dev
1044 including /dev/.udev/, find the links to /sys and end up stat()'ing sysfs files
1045 million times. This takes ages on slow boxes.
1047 The udevinfo attribute walk (-a) now works with giving a device node
1048 name (-n) instead of a devpath (-p). The query now always works, also when
1049 no database file was created by udev.
1051 The built-in /etc/passwd /etc/group parser is removed, we always depend on
1052 getpwnam() and getgrnam() now. One of the next releases will depend on
1053 fnmatch() and may use getopt_long().
1057 Bugfixes and small improvements.
1061 Fix path_id for recent kernels.
1067 Added support for swapping network interface names, by temporarily
1068 renaming the device and wait for the target name to become free.
1072 The built-in MODALIAS key and substitution is removed.
1076 The binary firmware helper is replaced by the usual simple
1077 shell script. Udevsend is removed from the tree.
1085 Some more keys require the correct use of '==' and '=' depending
1086 on the kind of operation beeing an assignment or a match. Rules
1087 with invalid operations are skipped and logged to syslog. Please
1088 test with udevtest if the parsing of your rules throws errors and
1089 fix possibly broken rules.
1093 Provide "udevsettle" to wait for all current udev events to finish.
1094 It also watches the current kernel netlink queue by comparing the
1095 even sequence number to make sure that there are no current pending
1096 events that have not already arrived in the daemon.
1100 Fix rule to skip persistent rules for removable IDE devices, which
1101 also skipped optical IDE drives.
1103 All *_id program are installed in /lib/udev/ by default now.
1105 No binary is stripped anymore as this should be done in the
1106 packaging process and not at build time.
1108 libvolume_id is provided as a shared library now and vol_id is
1109 linked against it. Also one of the next HAL versions will require
1110 this library, and the HAL build process will also require the
1111 header file to be installed. The copy of the same code in HAL will
1112 be removed to have only a single copy left on the system.
1116 Add persistent links for SCSI tapes. The rules file is renamed
1117 to 60-persistent-storage.rules.
1119 Create persistent path for usb devices. Can be used for all sorts
1120 of devices that can't be distinguished by other properties like
1121 multiple identical keyboards and mice connected to the same box.
1123 Provide "udevtrigger" program to request events on coldplug. The
1124 shell script is much too slow with thousends of devices.
1128 Fix persistent disk rules to exclude removable IDE drives.
1130 Warn if %e, $modalias or MODALIAS is used.
1134 Fix queue export, which wasn't correct for subsequent add/remove
1135 events for the same device.
1139 Fix cramfs detection on big endian.
1141 Make WAIT_FOR_SYSFS usable in "normal" rules and silent if the whole
1146 If BUS== and SYSFS{}== have been used in the same rule, the sysfs
1147 attributes were only checked at the parent device that matched the
1148 by BUS requested subsystem. Fix it to also look at the device we
1149 received the event for.
1151 Build variable CROSS has changed to CROSS_COMPILE to match the kernel
1156 Fix a bug where NAME="" would prevent RUN from beeing executed.
1158 RUN="/bin/program" does not longer automatically add the subsystem
1159 as the first parameter. This is from the days of /sbin/hotplug
1160 which is dead now and it's just confusing to need to add a space at
1161 the end of the program name to prevent this.
1162 If you use rules that need the subsystem as the first parameter,
1163 like the old "udev_run_hotlugd" and "udev_run_devd", add the subsystem
1164 to the key like RUN+="/bin/program $env{SUBSYSTEM}".
1168 The udev man page has moved to udev(7) as it does not describe a command
1169 anymore. The programs udev, udevstart and udevsend are no longer installed
1170 by default and must be copied manually, if they should be installed or
1171 included in a package.
1173 Fix a bug where "ignore_device" could run earlier collected RUN keys before
1174 the ignore rule was applied.
1176 More preparation for future sysfs changes. usb_id and scsi_id no longer
1177 depend on a magic order of devices in the /devices chain. Specific devices
1178 should be requested by their subsytem.
1180 This will always find the scsi parent device without depending on a specific
1182 dev = sysfs_device_get(devpath);
1183 dev_usb = sysfs_device_get_parent_with_subsystem(dev, "scsi");
1185 The "device" link in the current sysfs layout will be automatically
1186 _resolved_ as a parent and in the new sysfs layout it will just _be_ the
1187 parent in the devpath. If a device is requested by it's symlink, like all
1188 class devices in the new sysfs layout will look like, it gets automatically
1189 resolved and substituted with the real devpath and not the symlink path.
1192 A similar logic must be applied to _all_ sysfs users, including
1193 scripts, that search along parent devices in sysfs. The explicit use of
1194 the "device" link must be avoided. With the future sysfs layout all
1195 DEVPATH's will start with /devices/ and have a "subsystem" symlink poiting
1196 back to the "class" or the "bus". The layout of the parent devices in
1197 /devices is not necessarily expected to be stable across kernel releases and
1198 searching for parents by their subsystem should make sysfs users tolerant
1199 for changed parent chains.
1203 Prepare udev to work with the experimental kernel patch, that moves
1204 /sys/class devices to /sys/devices and /sys/block to /sys/class/block.
1206 Clarify BUS, ID, $id usage and fix $id behavior. This prepares for
1207 moving the class devices to /sys/devices.
1209 Thanks again to Marco for help finding a hopefully nice compromise
1210 to make %b simpler and working again.
1214 Complete removal of libsysfs, replaced by simple helper functions
1215 which are much simpler and a bit faster. The udev daemon operatesentirely
1216 on event parameters and does not use sysfs for simple rules anymore.
1217 Please report any new bugs/problems, that may be caused by this big
1218 change. They will be fixed immediately.
1220 The enumeration format character '%e' is deprecated and will be
1221 removed sometimes from a future udev version. It never worked correctly
1222 outside of udevstart, so we can't use it with the new parallel
1223 coldplug. A simple enumeration is as useless as the devfs naming
1224 scheme, just get rid of both if you still use it.
1226 MODALIAS and $modalias is not needed and will be removed from one of
1227 the next udev versions, replace it in all rules with ENV{MODALIAS} or
1228 the sysfs "modalias" value.
1230 Thanks a lot to Marco for all his help on finding and fixing bugs.
1234 Let scsi_id request libata drive serial numbers from page 0x80.
1236 Renamed etc/udev/persistent.rules to persistent-disk.rules and
1237 added /dev/disk/by-name/* for device mapper device names.
1239 Removed %e from the man page. It never worked reliably outside
1240 of udevstart and udevstart is no longer recommended to use.
1244 Symlinks are now exported to the event environment. Hopefully it's no
1245 longer needed to run udevinfo from an event process, like it was
1246 mentioned on the hotplug list:
1247 UDEV [1134776873.702967] add@/block/sdb
1250 DEVLINKS=/dev/disk/by-id/usb-IBM_Memory_Key_0218B301030027E8 /dev/disk/by-path/usb-0218B301030027E8:0:0:0
1254 Fix a problem if udevsend is used as the hotplug handler and tries to use
1255 syslog, which causes a "vc" event loop. 2.6.15 will make udevsend obsolete
1256 and this kind of problems will hopefully go away soon.
1260 All built-in logic to work around bad sysfs timing is removed with this
1261 version. The need to wait for sysfs files is almost fixed with a kernel
1262 version that doesn't work with this udev version anyway. Until we fix
1263 the timing of the "bus" link creation, the former integrated logic should
1264 be emulated by a rule placed before all other rules:
1265 ACTION=="add", DEVPATH=="/devices/*", ENV{PHYSDEVBUS}=="?*", WAIT_FOR_SYSFS="bus"
1267 The option "udev_db" does no longer exist. All udev state will be in
1268 /$udev_root/.udev/ now, there is no longer an option to set this
1270 If the init script or something else used this value, just depend on
1271 this hardcoded path. But remember _all_content_ of this directory is
1272 still private to udev and can change at any time.
1274 Default location for rule sripts and helper programs is now: /lib/udev/.
1275 Everything that is not useful on the commandline should go into this
1276 directory. Some of the helpers in the extras folder are installed there
1277 now. The rules need to be changed, to find the helpers there.
1279 Also /lib/udev/devices is recommended as a directory where packages or
1280 the user can place real device nodes, which get copied over to /dev at
1281 every boot. This should replace the various solutions with custom config
1284 Udevsend does no longer start the udev daemon. This must be done with
1285 the init script that prepares /dev on tmpfs and creates the initial nodes,
1286 before starting the daemon.
1290 Silent a too verbose error logging for the old hotplug.d/ dev.d/
1293 The copy of klibc is removed. A systemwide installed version of klibc
1294 should be used to build a klibc udev now.
1298 NAME="" will not create any nodes, but execute RUN keys. To completely
1299 ignore an event the OPTION "ignore_device" should be used.
1301 After removal of the reorder queue, events with a TIMEOUT can be executed
1302 without any queuing now.
1306 Fixed bug in udevd, if inotify is not available. We depend on netlink
1307 uevents now, kernels without that event source will not work with that
1308 version of udev anymore.
1312 The rule parsing happens now in the daemon once at startup, all udev
1313 event processes inherit the already parsed rules from the daemon.
1314 It is shipped with SUSE10.0 and reduces heavily the system load at
1315 startup. The option to save precompiled rules and let the udev process
1316 pick the them up is removed, as it's no longer needed.
1318 Kernel 2.6.15 will have symlinks at /class/input pointing to the real
1319 device. Libsysfs is changed to "translate" the requested link into the
1320 real device path, as it would happen with the hotplug event. Otherwise
1321 device removal and the udev database will not work.
1323 Using 'make STRIPCMD=' will leave the binaries unstripped for debugging
1326 A few improvements for vol_id, the filesytem probing code.
1330 Fix a stupid typo in extras/run_directory for "make install".
1332 scsi_id creates the temporary devnode now in /dev for usage with a
1333 non-writable /tmp directory.
1335 The uevent kernel socket buffer can carry app. 50.000 events now,
1336 let's see who can break this again. :)
1338 The upcoming kernel will have a new input driver core integration.
1339 Some class devices are now symlinks to the real device. libsysfs
1340 needs a fix for this to work correctly. Udevstart of older udev
1341 versions will _not_ create these devices!
1345 Fix a 'install' target in the Makefile, that prevents EXTRAS from
1350 A bunch of mostly trivial bugfixes. From now on no node name or
1351 symlink name can contain any character than plain whitelisted ascii
1352 characters or validated utf8 byte-streams. This is needed for the
1353 /dev/disk/by-label/* links, because we import untrusted data and
1354 export it to the filesystem.
1358 More bugfixes. If udevd was started from the kernel, we don't
1359 have stdin/stdout/stderr, which broke the forked tools in some
1364 Bugfix. udevstart event ordering was broken for a long time.
1365 The new run_program() uncovered it, because /dev/null was not
1366 available while we try to run external programs.
1367 Now udevstart should create it before we run anything.
1371 Minor bugfixes and some distro rules updates. If you don't have the
1372 persistent disk rules in /dev/disk/by-*/* on your distro, just
1373 grab it from here. :)
1377 We can use socket communication now to pass events from udev to
1379 RUN+="socket:/org/freedesktop/hal/udev_event"
1380 will pass the whole udev event to the HAL daemon without the need
1381 for a forked helper. (See ChangeLog for udevmonitor, as an example)
1385 Mostly bugfixes and see ChangeLog.
1387 The test for the existence of an environment value should be
1389 ENV{KEY}=="*" to ENV{KEY}=="?*"
1390 because "*" will not fail anymore, if the key does not exist or
1395 Bugfixes and a few tweaks described in the ChangeLog.
1399 Mostly a Bugfix release.
1401 Added WAIT_FOR_SYSFS="<attribute>" to be able to fight against the sysfs
1402 timing with custom rules.
1406 We changed the internal rule storage format. Our large rule files took
1407 2 MB of RAM, with the change we are down to 99kB.
1409 If the device-node has been created with default name and no symlink or
1410 options are to remenber, it is not longer stored in the udevdb. HAL will
1411 need to be updated to work correctly with that change.
1413 To overrride optimization flags, OPTFLAGS may be used now.
1421 Major changes happened with this release. The goal is to take over the
1422 complete kernel-event handling and provide a more efficient way to dispatch
1423 kernel events. Replacing most of the current shell script logic and the
1424 kernel forked helper with a netlink-daemon and a rule-based event handling.
1426 o udevd listens to netlink events now. The first valid netlink event
1427 will make udevd ignore any message from udevsend that contains a
1428 SEQNUM, to avoid duplicate events. The forked events can be disabled
1430 echo "" > /proc/sys/kernel/hotplug
1431 For full support, the broken input-subsytem needs to be fixed, not to
1432 bypass the driver core.
1434 o /etc/dev.d/ + /etc/hotplug.d/ directory multiplexing is completely
1435 removed from udev itself and must be emulated by calling small
1436 helper binaries provided in the extras folder:
1437 make EXTRAS=extras/run_directory/
1438 will build udev_run_devd and udev_run_hotplugd, which can be called
1439 from a rule if needed:
1440 RUN+="/sbin/udev_run_hotplugd"
1441 The recommended way to handle this is to convert all the calls from
1442 the directories to explicit udev rules and get completely rid of the
1443 multiplexing. (To catch a ttyUSB event, you now no longer need to
1444 fork and exit 300 tty script instances you are not interested in, it
1445 is just one rule that matches exactly the device.)
1447 o udev handles now _all_ events not just events for class and block
1448 devices, this way it is possible to control the complete event
1449 behavior with udev rules. Especially useful for rules like:
1450 ACTION="add", DEVPATH="/devices/*", MODALIAS=="?*", RUN+="/sbin/modprobe $modalias"
1452 o As used in the modalias rule, udev supports now textual
1453 substitution placeholder along with the usual format chars. This
1454 needs to be documented, for now it's only visible in udev_rules_parse.c.
1456 o The rule keys support now more operations. This is documented in the
1457 man page. It is possible to add values to list-keys like the SYMLINK
1458 and RUN list with KEY+="value" and to clear the list by assigning KEY="".
1459 Also "final"-assignments are supported by using KEY:="value", which will
1460 prevent changing the key by any later rule.
1462 o kernel 2.6.12 has the "detached_state" attribute removed from
1463 sysfs, which was used to recognize sysfs population. We switched that
1464 to wait for the "bus" link, which is only available in kernels after 2.6.11.
1465 Running this udev version on older kernels may cause a short delay for
1468 o To provide infrastructure for persistent device naming, the id programs:
1469 scsi_id, vol_id (former udev_volume_id), and ata_id (new) are able now
1470 to export the probed data in environment key format:
1471 pim:~ # /sbin/ata_id --export /dev/hda
1472 ID_MODEL=HTS726060M9AT00
1473 ID_SERIAL=MRH401M4G6UM9B
1474 ID_REVISION=MH4OA6BA
1476 The following rules:
1477 KERNEL="hd*[!0-9]", IMPORT="/sbin/ata_id --export $tempnode"
1478 KERNEL="hd*[!0-9]", ENV{ID_SERIAL}=="?*", SYMLINK+="disk/by-id/$env{ID_MODEL}_$env{ID_SERIAL}"
1481 kay@pim:~> tree /dev/disk
1484 | |-- HTS726060M9AT00_MRH401M4G6UM9B -> ../../hda
1485 | `-- IBM-Memory_Key -> ../../sda
1487 | |-- swap -> ../../hda1
1488 | |-- date -> ../../sda1
1489 | `-- home -> ../../hda3
1491 |-- 2E08712B0870F2E7 -> ../../hda3
1492 |-- 9352cfef-7687-47bc-a2a3-34cf136f72e1 -> ../../hda1
1493 |-- E845-7A89 -> ../../sda1
1494 `-- b2a61681-3812-4f13-a4ff-920d70604299 -> ../../hda2
1496 The IMPORT= operation will import these keys in the environment and make
1497 it available for later PROGRAM= and RUN= executed programs. The keys are
1498 also stored in the udevdb and can be queried from there with one of the
1501 o A few binaries are silently added to the repository, which can be used
1502 to replay kernel events from initramfs instead of using coldplug. udevd
1503 can be instructed now to queue-up events while the stored events from
1504 initramfs are filled into the udevd-queue. This code is still under
1505 development and there is no documentation now besides the code itself.
1506 The additional binaries get compiled, but are not installed by default.
1508 o There is also a temporary fix for a performance problem where too many
1509 events happen in parallel and every event needs to parse the rules.
1510 udev can now read precompiled rules stored on disk. This is likely to be
1511 replaced by a more elegant solution in a future udev version.
1515 With kernel version 2.6.12, the sysfs file "detached_state" was removed.
1516 Fix for libsysfs not to expect this file was added.
1520 All rules are applied now, but only the first matching rule with a NAME-key
1521 will be applied. All later rules with NAME-key are completely ignored. This
1522 way system supplied symlinks or permissions gets applied to user-defined
1526 Please check your rules setup, if you may need to add OPTIONS="last_rule"
1527 to some rules, to keep the old behavior.
1529 The rules are read on "remove"-events too. That makes is possible to match
1530 with keys that are available on remove (KERNEL, SUBSYSTEM, ID, ENV, ...) to
1531 instruct udev to ignore an event (OPTIONS="ignore_device").
1532 The new ACTION-key may be used to let a rule act only at a "remove"-event.
1534 The new RUN-key supports rule-based execution of programs after device-node
1535 handling. This is meant as a general replacement for the dev.d/-directories
1536 to give fine grained control over the execution of programs.
1538 The %s{}-sysfs format char replacement values are searched at any of the
1539 devices in the device chain now, not only at the class-device.
1541 We support log priority levels now. The value udev_log in udev.conf is used
1542 to determine what is printed to syslog. This makes it possible to
1543 run a version with compiled-in debug messages in a production environment
1544 which is sometimes needed to find a bug.
1545 It is still possible to supress the inclusion of _any_ syslog usage with
1546 USE_LOG=false to create the smallest possible binaries if needed.
1547 The configured udev_log value can be overridden with the environment variable
1552 Possible use of a system-wide klibc:
1553 make USE_KLIBC=true KLCC=/usr/bin/klcc all
1554 will link against an external klibc and our own version will be ignored.
1558 We support an unlimited count of symlinks now.
1560 If USE_STATIC=true is passed to a glibc build, we link statically and use
1561 a built-in userdb parser to resolve user and group names.
1563 The PLACE= key is gone. It can be replaced by an ID= for a long time, because
1564 we walk up the chain of physical devices to find a match.
1566 The KEY="<value>" format supports '=', '==', '!=,' , '+=' now. This makes it
1567 easy to skip certain attribute matches without composing rules with weird
1568 character class negations like:
1569 KERNEL="[!s][!c][!d]*"
1570 this can now be replaced with:
1572 The current simple '=' is still supported, and should work as it does today,
1573 but existing rules should be converted if possible, to be better readable.
1575 We have new ENV{}== key now, to match against a maximum of 5 environment
1578 udevstart is its own binary again, because we don't need co carry this araound
1579 with every forked event.