what dictates which devices gets an entry in /dev?
Linux - NewbieThis Linux forum is for members that are new to Linux.
Just starting out and have a question?
If it is not in the man pages or the how-to's this is the place!
Notices
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Whether you are a digital nomad or just looking for flexibility, Shells can put your Linux machine on the device that you want to use.
Exclusive for LQ members, get up to 45% off per month. Click here for more info.
what dictates which devices gets an entry in /dev?
Hi,
When kernel boots up, there are a number of devices list in /dev. My question is, through what mechanism do we tell the kernel which device to be add to/remove from /dev on power up? (I am not talking about creating/deleting a node at run time)
Thanks for the response!
@Smokey_justme, so some scripts are executed to call udev (or its variants) to populate /dev at boot time? Could you provide a bit more details?
Pff, basically after udev is started, it will load all devices, populate dev according to found devices (or newly connected), load the module, if one exists, execute custom scripts if needed, etc..
While in general udev does the same thing, the location of the files and the moment it populates /dev depends from distribution to distribution..
Also, on some distributions, you might run an initial initrd image (basically, before everything is booted, a small image is used containing the necessary modules/drivers that need preloaded in order for the system to boot -- think RAID, LVM, encrypted partitions --- at that point no udev is loaded, so the /dev is "manually" pre-populated with a minimal set of devices)
During the initrd startup, the command "mount -t devtmpfs none /dev" is done. devtmpfs is built into the kernel and provides a map of the indentified devices during hardware initialization. The identified devices are already present in /dev at that point. udevd can add updates (by loading drivers based on events from controllers).
LinuxQuestions.org is looking for people interested in writing
Editorials, Articles, Reviews, and more. If you'd like to contribute
content, let us know.