3 We changed the internal rule storage format. Our large rule files took
4 2 MB of RAM, with the change we are down to 99kB.
6 If the device-node has been created with default name and no symlink or
7 options are to remenber, it is not longer stored in the udevdb. HAL will
8 need to be updated to work correctly with that change.
10 To overrride optimization flags, OPTFLAGS may be used now.
18 Major changes happened with this release. The goal is to take over the
19 complete kernel-event handling and provide a more efficient way to dispatch
20 kernel events. Replacing most of the current shell script logic and the
21 kernel forked helper with a netlink-daemon and a rule-based event handling.
23 o udevd listens to netlink events now. The first valid netlink event
24 will make udevd ignore any message from udevsend that contains a
25 SEQNUM, to avoid duplicate events. The forked events can be disabled
27 echo "" > /proc/sys/kernel/hotplug
28 For full support, the broken input-subsytem needs to be fixed, not to
29 bypass the driver core.
31 o /etc/dev.d/ + /etc/hotplug.d/ directory multiplexing is completely
32 removed from udev itself and must be emulated by calling small
33 helper binaries provided in the extras folder:
34 make EXTRAS=extras/run_directory/
35 will build udev_run_devd and udev_run_hotplugd, which can be called
36 from a rule if needed:
37 RUN+="/sbin/udev_run_hotplugd"
38 The recommended way to handle this is to convert all the calls from
39 the directories to explicit udev rules and get completely rid of the
40 multiplexing. (To catch a ttyUSB event, you now no longer need to
41 fork and exit 300 tty script instances you are not interested in, it
42 is just one rule that matches exactly the device.)
44 o udev handles now _all_ events not just events for class and block
45 devices, this way it is possible to control the complete event
46 behavior with udev rules. Especially useful for rules like:
47 ACTION="add", DEVPATH="/devices/*", MODALIAS=="?*", RUN+="/sbin/modprobe $modalias"
49 o As used in the modalias rule, udev supports now textual
50 substitution placeholder along with the usual format chars. This
51 needs to be documented, for now it's only visible in udev_rules_parse.c.
53 o The rule keys support now more operations. This is documented in the
54 man page. It is possible to add values to list-keys like the SYMLINK
55 and RUN list with KEY+="value" and to clear the list by assigning KEY="".
56 Also "final"-assignments are supported by using KEY:="value", which will
57 prevent changing the key by any later rule.
59 o kernel 2.6.12 has the "detached_state" attribute removed from
60 sysfs, which was used to recognize sysfs population. We switched that
61 to wait for the "bus" link, which is only available in kernels after 2.6.11.
62 Running this udev version on older kernels may cause a short delay for
65 o To provide infrastructure for persistent device naming, the id programs:
66 scsi_id, vol_id (former udev_volume_id), and ata_id (new) are able now
67 to export the probed data in environment key format:
68 pim:~ # /sbin/ata_id --export /dev/hda
69 ID_MODEL=HTS726060M9AT00
70 ID_SERIAL=MRH401M4G6UM9B
74 KERNEL="hd*[!0-9]", IMPORT="/sbin/ata_id --export $tempnode"
75 KERNEL="hd*[!0-9]", ENV{ID_SERIAL}=="?*", SYMLINK+="disk/by-id/$env{ID_MODEL}_$env{ID_SERIAL}"
78 kay@pim:~> tree /dev/disk
81 | |-- HTS726060M9AT00_MRH401M4G6UM9B -> ../../hda
82 | `-- IBM-Memory_Key -> ../../sda
84 | |-- swap -> ../../hda1
85 | |-- date -> ../../sda1
86 | `-- home -> ../../hda3
88 |-- 2E08712B0870F2E7 -> ../../hda3
89 |-- 9352cfef-7687-47bc-a2a3-34cf136f72e1 -> ../../hda1
90 |-- E845-7A89 -> ../../sda1
91 `-- b2a61681-3812-4f13-a4ff-920d70604299 -> ../../hda2
93 The IMPORT= operation will import these keys in the environment and make
94 it available for later PROGRAM= and RUN= executed programs. The keys are
95 also stored in the udevdb and can be queried from there with one of the
98 o A few binaries are silently added to the repository, which can be used
99 to replay kernel events from initramfs instead of using coldplug. udevd
100 can be instructed now to queue-up events while the stored events from
101 initramfs are filled into the udevd-queue. This code is still under
102 development and there is no documentation now besides the code itself.
103 The additional binaries get compiled, but are not installed by default.
105 o There is also a temporary fix for a performance problem where too many
106 events happen in parallel and every event needs to parse the rules.
107 udev can now read precompiled rules stored on disk. This is likely to be
108 replaced by a more elegant solution in a future udev version.
112 With kernel version 2.6.12, the sysfs file "detached_state" was removed.
113 Fix for libsysfs not to expect this file was added.
117 All rules are applied now, but only the first matching rule with a NAME-key
118 will be applied. All later rules with NAME-key are completely ignored. This
119 way system supplied symlinks or permissions gets applied to user-defined
123 Please check your rules setup, if you may need to add OPTIONS="last_rule"
124 to some rules, to keep the old behavior.
126 The rules are read on "remove"-events too. That makes is possible to match
127 with keys that are available on remove (KERNEL, SUBSYSTEM, ID, ENV, ...) to
128 instruct udev to ignore an event (OPTIONS="ignore_device").
129 The new ACTION-key may be used to let a rule act only at a "remove"-event.
131 The new RUN-key supports rule-based execution of programs after device-node
132 handling. This is meant as a general replacement for the dev.d/-directories
133 to give fine grained control over the execution of programs.
135 The %s{}-sysfs format char replacement values are searched at any of the
136 devices in the device chain now, not only at the class-device.
138 We support log priority levels now. The value udev_log in udev.conf is used
139 to determine what is printed to syslog. This makes it possible to
140 run a version with compiled-in debug messages in a production environment
141 which is sometimes needed to find a bug.
142 It is still possible to supress the inclusion of _any_ syslog usage with
143 USE_LOG=false to create the smallest possible binaries if needed.
144 The configured udev_log value can be overridden with the environment variable
149 Possible use of a system-wide klibc:
150 make USE_KLIBC=true KLCC=/usr/bin/klcc all
151 will link against an external klibc and our own version will be ignored.
155 We support an unlimited count of symlinks now.
157 If USE_STATIC=true is passed to a glibc build, we link statically and use
158 a built-in userdb parser to resolve user and group names.
160 The PLACE= key is gone. It can be replaced by an ID= for a long time, cause
161 we walk up the chain of physical devices to find a match.
163 The KEY="<value>" format supports '=', '==', '!=,' , '+=' now. This makes it
164 easy to skip certain attribute matches without composing rules with weird
165 character class negations like:
166 KERNEL="[!s][!c][!d]*"
167 this can now be replaced with:
169 The current simple '=' is still supported, and should work as it does today,
170 but existing rules should be converted if possible, to be better readable.
172 We have new ENV{}== key now, to match against a maximum of 5 environment
175 udevstart is its own binary again, cause we don't need co carry this araound
176 with every forked event.