The end of the devfs story

Almost one year ago, the kernel developers decided to formally recognize the new development model, where large changes were welcome in the stable 2.6 series. At that time, Greg Kroah-Hartman decided to test out the new model by posting a patch to remove devfs. The devfs filesystem, a virtual filesystem which provides a dynamic /dev directory, had been unpopular with many kernel developers since long before it was merged in 2.3.46. It was never enabled by most distributions, and, in more recent times, had seen little maintenance. Meanwhile, the user-space udev utility had developed to the point where it could fill in for devfs. Since there was no 2.7 on the horizon, and 2.6 was officially open to user-visible changes, it seemed like a good time to close the devfs chapter forevermore.

Except that, as it turns out, the developers were not quite ready to eliminate a user-visible feature on such short notice. After some discussion, it was decided that changes of this kind should happen after a one-year warning period. As a result, a file was created in the Documentation directory (here's the almost-2.6.12 version) which listed features scheduled for removal and the target date. Devfs went into the file, with July, 2005 as the time for its ultimate demise.

July is nearly here, and Greg has not forgotten. He has returned with a 22-part patch which removes every trace of devfs from a surprisingly large portion of the kernel. It would seem that devfs had gotten its fingers into just about everything. In the absence of some sort of surprise, this patch seems certain to be merged for 2.6.13. If there are any devfs users out there, they have gotten their last warning.

Index entries for this article
Kernel	Development model
Kernel	devfs

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to post comments

The end of the devfs story

Posted Jun 16, 2005 7:22 UTC (Thu) by tao (subscriber, #17563) [Link] (2 responses)

... and there was much rejoicement!

The end of the devfs story

Posted Jun 16, 2005 10:45 UTC (Thu) by Felix.Braun (guest, #3032) [Link] (1 responses)

I've always been a fan of a dynamic /dev directory. Maybe the approach taken by Richard Gooch with devfs to include this in kernel space was technically suboptimal because it included too many policy decisions ("disc" vs. "disk"). However, one has to note that sysfs, the user space interface that udev uses to manage the dynamic creation of device nodes, was non existant at the time devfs was created. In a way, the opposition against devfs probably sparked the creation of the technically superior solution using sysfs and udev we have nowadays.

The end of the devfs story

Posted Jun 16, 2005 11:33 UTC (Thu) by alex (subscriber, #1355) [Link]

In a way, the opposition against devfs probably sparked the creation of the technically superior solution using sysfs and udev we have nowadays.

It is the way of things in the Open Source world ;-)

I must say my limited experience with udev so far has been a pleasent experience. I can only wish we had such a stable solution when I was hacking embedded linux a couple of years ago on 2.4...

The end of the devfs story

Posted Jun 16, 2005 19:59 UTC (Thu) by NightMonkey (subscriber, #23051) [Link]

Yay! UDEV works well on my systems, and it makes so much more sense than devfs, at least to me. Thanks, UDEV devs!