diff options
Diffstat (limited to 'README')
| -rw-r--r-- | README | 45 |
1 files changed, 21 insertions, 24 deletions
@@ -7,7 +7,7 @@ does not recommend replacing a distro's udev installation with the upstream version. The upstream udev project's set of default rules may require a most recent -kernel release to work properly. This is currently version 2.6.32. +kernel release to work properly. Tools and rules shipped by udev are not public API and may change at any time. Never call any private tool in /usr/lib/udev from any external application; it @@ -22,26 +22,30 @@ Requirements: - Some architectures might need a later kernel, that supports accept4(), or need to backport the accept4() syscall wiring in the kernel. - - These options are needed: + - These options are required: + CONFIG_DEVTMPFS=y CONFIG_HOTPLUG=y - CONFIG_UEVENT_HELPER_PATH="" + CONFIG_INOTIFY_USER=y CONFIG_NET=y - CONFIG_UNIX=y - CONFIG_SYSFS=y - CONFIG_SYSFS_DEPRECATED*=n CONFIG_PROC_FS=y - CONFIG_INOTIFY_USER=y CONFIG_SIGNALFD=y + CONFIG_SYSFS=y + CONFIG_SYSFS_DEPRECATED*=n + CONFIG_UEVENT_HELPER_PATH="" - These options might be needed: - CONFIG_TMPFS=y - CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes) CONFIG_BLK_DEV_BSG=y (SCSI devices) + CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes) + + - The /dev directory needs the 'devtmpfs' filesystem mounted. + Udev only manages the permissions and ownership of the + kernel-provided device nodes, and possibly creates additional symlinks. - - Udev does not work with the CONFIG_SYSFS_DEPRECATED* option. + - Udev requires /run to be writable, which is usually done by mounting a + 'tmpfs' filesystem. - - Unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work, - but it is not supported. + - This version of udev does not work properly with the CONFIG_SYSFS_DEPRECATED* + option enabled. - The deprecated hotplug helper /sbin/hotplug should be disabled in the kernel configuration, it is not needed today, and may render the system @@ -59,26 +63,19 @@ Requirements: available. - Some udev extras have external dependencies like: - libacl, libglib2, usbutils, pciutils, and gperf. + libglib2, usbutils, pciutils, and gperf. All these extras can be disabled with configure options. Setup: - - At bootup, the /dev directory should get the 'devtmpfs' filesystem - mounted. Udev manages the permissions and ownership of the kernel-created - device nodes, and udev possibly creates additional symlinks. If needed, udev also - works on an empty 'tmpfs' filesystem, but some device nodes like - /dev/null, /dev/console, /dev/kmsg should be created before udevd is started. - - The udev daemon should be started to handle device events sent by the kernel. During bootup, the events for already existing devices can be replayed, so - that they are configured by udev. This is usually done by: - udevadm trigger --action=add --type=subsystems - udevadm trigger --action=add --type=devices + that they are configured by udev. The systemd service files contain the + needed commands to start the udev daemon and the coldplug sequence. - Restarting the daemon never applies any rules to existing devices. - - New/changed rule files are picked up automatically; there is no daemon - restart or signal needed. + - New/changed rule files are picked up automatically; there is usually no + daemon restart or signal needed. Operation: - Based on events the kernel sends out on device creation/removal, udev |