Armin K. wrote:
On 24.5.2015 18:06, Bruce Dubbs wrote:
Actually I've been toying with the idea of using a custom script to make a series of mknod commands to add things I need at boot. Then I can skip udev completely. In the final analysis, what does it add for us? About the only thing I can think of that affects most users is that it may change some permissions in /dev.
Udev doesn't create any device nodes for some time now. It's handled by devtmpfs. What it does is: It changes permissions, creates symlinks and in certain cases, renames device nodes. It monitors devices addition and removals which is done by kernel (hotplug) and, depending on the nature of the device, applies a certain rule upon it, such as create a generic symlink, set up permissions, ownership, renaming, etc. The latter is important for some software, where it relies on udev through libudev to notify them about device additions and removals. One such software is Xorg's input drivers, which is why you can plug in a mouse after X server has been started and it will be recognised automatically, without having a need to restart the Xorg server and configure the device through xorg.conf. There are other packages that rely on libudev for similar stuff and it's mostly related to handing external devices such as printers, scanners, cameras (web cameras and professional digital cameras), etc. USB device handling through libusb-1 is done through libudev too.
Yes, for most workstations, it generally is only useful for usb devices. For a server, we may not want to even enable usb. There may be a need for dynamic hotplug of pci devices or scsi drives on a server, but I think that could be done without udev.
On a lot of servers, such as those used for the linuxfromscratch.org servers, there is no capability to plug in any device.
-- Bruce -- http://lists.linuxfromscratch.org/listinfo/blfs-support FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
