Ummm... devfs?

Posted Nov 18, 2002 22:29 UTC (Mon) by dododge (guest, #2870)
In reply to: Ummm... devfs? by JLCdjinn
Parent article: What's to become of devfs?

Look for just "devfs" with Google. The first item in the list is the FAQ from the devfs maintainer.

In brief: the "/dev" directory contains device files. Traditionally this is just a normal directory, and is preloaded with files for every device you might ever have connected. For example there might be a whole bunch of device files related to SCSI tape drives even though you have never had a tape drive (or SCSI bus, for that matter) attached to the machine.

devfs replaces this static directory with one generated by the kernel at runtime. Device files are created and removed on the fly when the associated driver is loaded and unloaded. Under devfs, you can get a quick view of attached devices and loaded drivers by simply looking at the contents of /dev.

devfs does shuffle some things around, though. The traditional /dev structure is almost entirely flat, while devfs makes extensive use of subdirectories (and in some cases quite deep subdirectories). Applications looking for certain device files might have to know about both the traditional and devfs locations for those files. Since not all applications actually do this, there's "devfsd", which is a daemon that can perform actions on device files. Probably the most common use for devfsd is to have it create symlinks from the "traditional" device locations to the equivalent "devfs" locations when the device comes up.