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The return of devfs

The return of devfs

Posted May 7, 2009 9:53 UTC (Thu) by vrfy (subscriber, #13362)
In reply to: The return of devfs by arjan
Parent article: The return of devfs

That's not quite right, distros don't do (needless) crack here. Some use braindead tools, which should not even exist in the first place, but that's a totally different story, which is not touched at all by devtmpfs.

Having static device nodes would be a very dangerous hack for a general purpose distro in the light of dynamic device numbers. You access a /dev name but you can't be sure, you talk to the right device. That's a problem you need to avoid for correctness, not for speed reasons. And we have many subsystems which have dynamic minors only. Even sd* disk nodes can be already, and likely will be dynamic for some systems pretty soon.

/dev needs to be on tmpfs these days for security reasons, because tools mess around here, and adding user access control lists to device nodes, and create tons of symlinks, which are only meaningful during the lifetime of a specific device.

Besides simplicity and reliability devtmpfs covers the transition time from the empty mounted tmpfs to the populated /dev. During this time, you can't do much else, but devtpmfs does not have that requirement at all, because /dev always reflects all currently known devices.


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