kay.sievers@vrfy.org
53921bfa44
On Thu, Jan 29, 2004 at 04:55:11PM +0100, Kay Sievers wrote: > On Thu, Jan 29, 2004 at 02:56:25AM +0100, Kay Sievers wrote: > > On Wed, Jan 28, 2004 at 10:47:36PM +0100, Kay Sievers wrote: > > > Oh, couldn't resist to try threads. > > > It's a multithreaded udevd that communicates through a localhost socket. > > > The message includes a magic with the udev version, so we don't accept > > > older udevsend's. > > > > > > No need for locking, cause we can't bind two sockets on the same address. > > > The daemon tries to connect and if it fails it starts the daemon. > > > > > > We create a thread for every incoming connection, handle over the socket, > > > sort the messages in the global message queue and exit the thread. > > > Huh, that was easy with threads :) > > > > > > With the addition of a message we wakeup the queue manager thread and > > > handle timeouts or move the message to the global exec list. This wakes > > > up the exec list manager who looks if a process is already running for this > > > device path. > > > If yes, the exec is delayed otherwise we create a thread that execs udev. > > > n the background. With the return of udev we free the message and wakeup > > > the exec list manager to look if something is pending. > > > > > > It is just a quick shot, cause I couldn't solve the problems with fork an > > > scheduling and I wanted to see if I'm to stupid :) > > > But if anybody with a better idea or more experience with I/O scheduling > > > we may go another way. The remaining problem is that klibc doesn't support > > > threads. > > > > > > By now, we don't exec anything, it's just a sleep 3 for every exec, > > > but you can see the queue management by watching syslog and do: > > > > > > DEVPATH=/abc ACTION=add SEQNUM=0 ./udevsend /abc > > Next version, switched to unix domain sockets. Next cleaned up version. Hey, nobody wants to try it :) Works for me, It's funny if I connect/disconnect my 4in1-usb-flash-reader every two seconds. The 2.6 usb rocks! I can connect/diconnect a hub with 3 devices plugged in every second and don't run into any problem but a _very_ big udevd queue.
udev - a userspace implementation of devfs
For more information on the design, and structure of this project, see the
files in the docs/ directory.
To use:
- You must be running a 2.6 version of the Linux kernel.
- Your 2.6 kernel must have had CONFIG_HOTPLUG enabled when it was built.
- Make sure sysfs is mounted. udev will figure out where sysfs is mounted, but
the traditional place for it is at /sys. You can mount it by hand by running:
mount -t sysfs none /sys
- Make sure you have the latest version of the linux-hotplug scripts. They are
available at linux-hotplug.sf.net or from your local kernel.org mirror at:
kernel.org/pub/linux/utils/kernel/hotplug/
They are required in order for udev to work properly.
If for some reason you do not install the hotplug scripts, you must tell the
kernel to point the hotplug binary at wherever you install udev at. This can
be done by:
echo "/sbin/udev" > /proc/sys/kernel/hotplug
- Build the project:
make
Note:
There are a number of different flags that you can use when building
udev. They are as follows:
prefix
set this to the default root that you want udev to be
installed into. This works just like the 'configure --prefix'
script does. Default value is ''. Only override this if you
really know what you are doing.
USE_KLIBC
if set to 'true', udev is built and linked against the
included version of klibc. Default value is 'false'.
USE_LOG
if set to 'true', udev will emit messages to the syslog when
it creates or removes device nodes. This is helpful to see
what udev is doing. This is enabled by default. Note, if you
are building udev against klibc it is recommended that you
disable this option (due to klibc's syslog implementation.)
USE_DBUS
if set to 'true', DBUS messages will be sent everytime udev
creates or removes a device node. This requires that DBUS
development headers and libraries be present on your system to
build properly. Default value is 'false'.
DEBUG
if set to 'true', debugging messages will be sent to the syslog
as udev is run. Default value is 'false'.
So, if you want to build udev using klibc with debugging messages, you
would do:
make USE_KLIBC=true DEBUG=true
Note: If you want to use klibc, you will have to set up the "linux"
symlink properly. See the file klibc/klibc/README and pay
attention to step "a)" there.
- Install the project:
make install
This will put the udev binary in /sbin, create the /udev and /etc/udev
directories, and place the udev configuration files in /etc/udev. You
will probably want to edit the namedev.* files to create custom naming
rules. More info on how the config files are set up are contained in
comments in the files, and is located in the documentation.
- Add and remove devices from the system and marvel as nodes are created
and removed in /udev/ based on the device types.
- If you later get sick of it, uninstall it:
make uninstall
Things are still quite rough, but it should work properly. If nothing
seems to happen, make sure your build worked properly by running the
udev-test.pl script as root in the test/ subdirectory of the udev source
tree.
Development and documentation help is very much appreciated, see the TODO
file for a list of things left to be done.
Any comment/questions/concerns please let me and the other udev developers
know by sending a message to the linux-hotplug-devel mailing list at:
linux-hotplug-devel@lists.sourceforge.net
greg k-h
greg@kroah.com