X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=FAQ;h=28f7552ae3c557b906596394f64b38f88c3bd274;hp=c082a5bec4d62fd443ee924f824090c3b90d0f0d;hb=84df02dd63bf53acb5a61e9db1da067760b927e9;hpb=b1830e7984e86c5765a67a3aae4b63e1c48155b6 diff --git a/FAQ b/FAQ index c082a5bec..28f7552ae 100644 --- a/FAQ +++ b/FAQ @@ -31,12 +31,31 @@ Q: But udev will not automatically load a driver if a /dev node is opened A: If you really require this functionality, then use devfs. It is still present in the kernel. -Q: But I really like the devfs naming scheme, will udev do that? +Q: But wait, I really want udev to automatically load drivers when they + are not present but the device node is opened. It's the only reason I + like using devfs. Please make udev do this. +A: No. udev is for managing /dev, not loading kernel drivers. + +Q: Oh come on, pretty please. It can't be that hard to do. +A: Such a functionality isn't needed on a properly configured system. All + devices present on the system should generate hotplug events, loading + the appropriate driver, and udev will notice and create the + appropriate device node. If you don't want to keep all drivers for your + hardware in memory, then use something else to manage your modules + (scripts, modules.conf, etc.) This is not a task for udev. + +Q: But I love that feature of devfs, please? +A: The devfs approach caused a lot of spurious modprobe attempts as + programs probed to see if devices were present or not. Every probe + attempt created a process to run modprobe, almost all of which were + spurious. + +Q: I really like the devfs naming scheme, will udev do that? A: Yes, udev can create /dev nodes using the devfs naming policy. A configuration file needs to be created to map the kernel default names - to the devfs names. Such a configuration file would be gladly added to - the udev package if it is provided by anyone who can create such a - mapping. + to the devfs names. See the initial udev.rules.devfs file in the udev + release. It is the start of such a configuration file. If there are + any things missing, please let the udev authors know. Q: What kinds of devices does udev create nodes for? A: All devices that are shown in sysfs will work with udev. If more @@ -51,7 +70,7 @@ A: udev is entirely in userspace. If the kernel supports a greater number of anonymous devices, udev will support it. Q: Will udev support symlinks? -A: Yes, patches are gladly accepted to add this functionality. +A: Yes, It now does. Multiple symlinks per device node too. Q: How will udev support changes to device permissions? A: On shutdown, udev will save the state of existing device permissions to @@ -65,6 +84,20 @@ Q: How will udev handle devices found before init runs? A: udev will be placed in initramfs and run for every device that is found. Work to get this implemented is still underway. +Q: Can I use udev to automount a USB device when I connect it? +A: Technically, yes, but udev is not intended for this. Projects that do + automount hotplugged storage devices are: + * Usb-mount http://users.actrix.co.nz/michael/usbmount.html + * devlabel http://linux.dell.com/projects.shtml#devlabel + + Alternatively, it is easy to add the following to fstab: + /udev/pendrive /pendrive vfat user,noauto 0 0 + + This means that users can access the device with: + $ mount /pendrive + And don't have to be root but will get full permissions on /pendrive. + This works even without udev if /udev/pendrive is replaced by /dev/sda1 + Q: I have other questions about udev, where do I ask them? A: The linux-hotplug-devel mailing list is the proper place for it. The address for it is linux-hotplug-devel@lists.sourceforge.net