11c17f75a
Denis Vlasenko
2009-04-19
Subject
mdev: enlarge inline documentation
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util-linux/mdev.c+22 -6
| @@ -15,6 +15,8 @@ | |
| * contains "4:0\n". Directory name is taken as device name, path component | |
| * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty". | |
| * Then mdev creates the /dev/device_name node. | |
| + | * If /sys/class/.../dev file does not exist, mdev still may act |
| + | * on this device: see "@|$|*command args..." parameter in config file. |
| * | |
| * mdev w/o parameters is called as hotplug helper. It takes device | |
| * and subsystem names from $DEVPATH and $SUBSYSTEM, extracts | |
| @@ -29,20 +31,34 @@ | |
| * | |
| * [-][subsystem/]device user:grp mode [>|=path] [@|$|*command args...] | |
| * [-]@maj,min[-min2] user:grp mode [>|=path] [@|$|*command args...] | |
| - | * |
| - | * The device name or "subsystem/device" combo is matched against 1st field |
| - | * (which is a regex), or maj,min is matched against 1st field. |
| + | * [-]$envvar=val user:grp mode [>|=path] [@|$|*command args...] |
| * | |
| * Leading minus in 1st field means "don't stop on this line", otherwise | |
| * search is stopped after the matching line is encountered. | |
| * | |
| - | * When line matches, the device node is created, chmod'ed and chown'ed. |
| - | * Then it moved to path, and if >path, a symlink to moved node is created |
| + | * The device name or "subsystem/device" combo is matched against 1st field |
| + | * (which is a regex), or maj,min is matched against 1st field, |
| + | * or specified environment variable (as regex) is matched against 1st field. |
| + | * |
| + | * $envvar=val format is useful for loading modules for hot-plugged devices |
| + | * which do not have driver loaded yet. In this case /sys/class/.../dev |
| + | * does not exist, but $MODALIAS is set to needed module's name |
| + | * (actually, an alias to it) by kernel. This rule instructs mdev |
| + | * to load the module and exit: |
| + | * $MODALIAS=.* 0:0 660 @modprobe "$MODALIAS" |
| + | * The kernel will generate another hotplug event when /sys/class/.../dev |
| + | * file appears. |
| + | * |
| + | * When line matches, the device node is created, chmod'ed and chown'ed, |
| + | * moved to path, and if >path, a symlink to moved node is created, |
| + | * all this if /sys/class/.../dev exists. |
| * Examples: | |
| * =loop/ - moves to /dev/loop | |
| * >disk/sda%1 - moves to /dev/disk/sdaN, makes /dev/sdaN a symlink | |
| - | * Then "command args" is executed (via sh -c 'command args'). |
| + | * |
| + | * Then "command args..." is executed (via sh -c 'command args...'). |
| * @:execute on creation, $:on deletion, *:on both. | |
| + | * This happens regardless of /sys/class/.../dev existence. |
| */ | |
| struct globals { | |