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78 lines
3.2 KiB
Plaintext
78 lines
3.2 KiB
Plaintext
udev - userspace device management
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For more information see the files in the docs/ directory.
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Important Note:
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Integrating udev in the system is a whole lot of work, has complex dependencies
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and differs a lot from distro to distro. All reasonable distros use udev these
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days, the major ones make it mandatory and the system will not work without it.
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The upstream udev project does not support or recomend to replace a distro's udev
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installation with the upstream version. The installation of a unmodified upstream
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version may render your system unusable! There is no "default" setup or a set
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of "default" rules provided by the upstream udev version.
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udev requires:
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- 2.6 version of the Linux kernel
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- the kernel must have sysfs, netlink, and hotplug enabled
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- proc must be mounted on /proc
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- sysfs must be mounted at /sys, no other location is supported
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- udev creates and removes device nodes in /dev based on events
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the kernel sends out on device discovery or removal
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- during bootup /dev usually gets a tmpfs mounted which is populated scratch
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by udev (created nodes don't survive a reboot, it always starts from scratch)
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- udev replaces the hotplug event management invoked from /sbin/hotplug
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by the udevd daemon, which receives the kernel events over netlink
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- all kernel events are matched against a set of specified rules which
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make it posible to hook into the event processing
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- there is a copy of the rules files for all major distros in the etc/udev
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directory (you may look there how others distros are doing it)
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Setting which are used for building udev:
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prefix
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set this to the default root that you want to use
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Only override this if you really know what you are doing
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DESTDIR
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prefix for install target for package building
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USE_LOG
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if set to 'true', udev will emit messages to the syslog when
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it creates or removes device nodes. This is helpful to see
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what udev is doing. This is enabled by default. Note, if you
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are building udev against klibc it is recommended that you
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disable this option (due to klibc's syslog implementation.)
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DEBUG
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if set to 'true', verbose debugging messages will be compiled into
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the udev binaries. Default value is 'false'.
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USE_SELINUX
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if set to 'true', udev will be built with SELinux support
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enabled. This is disabled by default.
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USE_KLIBC
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if set to 'true', udev is built and linked against the
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included version of klibc. Default value is 'false'.
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KERNEL_DIR
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If this is not set it will default to /lib/modules/`uname -r`/build
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This is used if USE_KLIBC=true to find the kernel include
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directory that klibc needs to build against. This must be set
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if you are not building udev while running a 2.6 kernel.
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EXTRAS
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if set, will build the "extra" helper programs as specified
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as listed (see below for an example.)
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if you want to build udev using klibc with debugging messages:
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make USE_KLIBC=true DEBUG=true
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if you want to build the udev helper program cdrom_id and scsi_id:
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make EXTRAS="extras/cdrom_id extras/scsi_id"
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Please direct any comment/question/concern to the linux-hotplug-devel mailing list at:
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linux-hotplug-devel@lists.sourceforge.net
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