Stefan Richter
1bbc1a9cb0
1. IIDC cameras from Point Grey use the vendor OUI as Specifier_ID instead of the 1394 TA's OUI but are otherwise fully compliant to the IIDC spec. Their device files should be accessible like those of any other IIDC cameras. 2. Originally, the Software_Version of devices that implement FCP (IEC 61883-1 Function Control Protocol) was meant to be a bitmap of all command sets that an FCP capable unit supports. Bitmap flags are defined for AV/C, CAL, EHS, HAVi, and vendor unique command sets. Software_Version was revised to be a simple identifier instead, and devices that support several command sets were meant to instantiate one unit directory for each command set. Still, some devices with the flags for AV/C and vendor unique command sets combined were released (but apparently no devices with any other flag combinations). These rare but existing AV/C + vendor unique devices need to be accessible just like plain AV/C devices. Side notes: - Many AV/C devices make use of the Vendor Dependent AV/C command, but this is unrelated to vendor unique FCP command sets. - Here are all standardized FireWire protocol identifiers that I know of, listed as Specifier_ID:Software_Version | specifier | protocol. 0x00005e:0x000001 | IANA | IPv4 over 1394 (RFC 2734) 0x00005e:0x000002 | IANA | IPv6 over 1394 (RFC 3146) 0x00609e:0x010483 | INCITS | SBP-2 (or SCSI command sets over SBP-3) 0x00609e:0x0105bb | INCITS | AV/C over SBP-3 0x00a02d:0x010001 | 1394 TA | AV/C (over FCP) 0x00a02d:0x010002 | 1394 TA | CAL 0x00a02d:0x010004 | 1394 TA | EHS 0x00a02d:0x010008 | 1394 TA | HAVi 0x00a02d:0x014000 | 1394 TA | Vendor Unique 0x00a02d:0x014001 | 1394 TA | Vendor Unique and AV/C (over FCP) 0x00a02d:0x000100 | 1394 TA | IIDC 1.04 0x00a02d:0x000101 | 1394 TA | IIDC 1.20 0x00a02d:0x000102 | 1394 TA | IIDC 1.30 0x00a02d:0x0A6BE2 | 1394 TA | DPP 1.0 0x00a02d:0x4B661F | 1394 TA | IICP 1.0 For now we are only interested in udev rules for AV/C and IIDC. Reported-by: Damien Douxchamps <ddsf@douxchamps.net> (Point Grey IIDC ID) Reported-by: Clemens Ladisch <clemens@ladisch.de> (AV/C + vendor unique ID) Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
udev - Linux userspace device management
Integrating udev in the system has complex dependencies and may differ from
distribution to distribution. A system may not be able to boot up or work
reliably without a properly installed udev version. The upstream udev project
does not recommend to replace 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 2.6.31.
Tools and rules shipped by udev are not public API and may change at any time.
Never call any private tool in /lib/udev from any external application, it might
just go away in the next release. Access to udev information is only offered
by udevadm and libudev. Tools and rules in /lib/udev, and the entire content of
the /dev/.udev directory is private to udev and does change whenever needed.
Requirements:
- Version 2.6.27 of the Linux kernel with sysfs, procfs, signalfd, inotify,
unix domain sockets, networking and hotplug enabled:
CONFIG_HOTPLUG=y
CONFIG_UEVENT_HELPER_PATH=""
CONFIG_NET=y
CONFIG_UNIX=y
CONFIG_SYSFS=y
CONFIG_SYSFS_DEPRECATED*=n
CONFIG_PROC_FS=y
CONFIG_TMPFS=y
CONFIG_INOTIFY_USER=y
CONFIG_SIGNALFD=y
CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes)
CONFIG_BLK_DEV_BSG=y (SCSI devices)
- Udev will not work with the CONFIG_SYSFS_DEPRECATED* option.
- Unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work,
but it is not supported.
- The deprecated hotplug helper /sbin/hotplug should be disabled in the
kernel configuration, it is not needed today, and may render the system
unusable because the kernel may create too many processes in parallel
so that the system runs out-of-memory.
- The proc filesystem must be mounted on /proc, the sysfs filesystem must
be mounted at /sys. No other locations are supported by a standard
udev installation.
- The system must have the following group names resolvable at udev startup:
disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem.
Especially in LDAP setups, it is required, that getgrnam() is able to resolve
these group names with only the rootfs mounted, and while no network is
available.
- To build all 'udev extras', libacl, libglib2, libusb, usbutils, pciutils,
gperf are needed. These dependencies can be disabled with the
--disable-extras configure option.
Setup:
- At bootup, the /dev directory should get the 'devtmpfs' filesystem
mounted. Udev will manage permissions and ownership of the kernel-created
device nodes, and possibly create additional symlinks. If needed, udev also
works on an empty 'tmpfs' filesystem, but some static device nodes like
/dev/null, /dev/console, /dev/kmsg are needed to be able to start udev itself.
- The udev daemon should be started to handle device events sent by the kernel.
During bootup, the kernel can be asked to send events for all already existing
devices, to apply the configuration to these devices. This is usually done by:
/sbin/udevadm trigger --type=subsystems
/sbin/udevadm trigger --type=devices
- Restarting the daemon does never apply any rules to existing devices.
- New/changed rule files are picked up automatically, there is no daemon
restart or signal needed.
Operation:
- Udev creates/removes device nodes in /dev, based on events the kernel
sends out on device creation/removal.
- All kernel events are matched against a set of specified rules, which
possibly hook into the event processing and load required kernel
modules to setup devices. For all devices the kernel exports a major/minor
number, if needed, udev will create a device node with the default kernel
name. If specified, udev applies permissions/ownership to the device
node, creates additional symlinks pointing to the node, and executes
programs to handle the device.
- The events udev handles, and the information udev merges into its device
database, can be accessed with libudev:
http://www.kernel.org/pub/linux/utils/kernel/hotplug/libudev/
http://www.kernel.org/pub/linux/utils/kernel/hotplug/gudev/
For more details about udev and udev rules see the udev(7) man page.
Please direct any comment/question to the linux-hotplug mailing list at:
linux-hotplug@vger.kernel.org