Re: devfs vs udev, thoughts from a devfs user

"Andrey Borzenkov"
2004-02-10T16:10:26Z

> I completely agree. But who would volunteer to spend their time fixing
> devfs if no one said they wanted devfs, if all evidence says everyone is
> happy with udev? I just wanted to get out that I'm not, I think devfs
> (as a concept, not neccessarily the implementation in the kernel right
> now) has merits udev does not and never will possess, and to see if anyone
> else agrees.

I am not happy with udev as it is currently; I am not happy with devfs crashing; I will continue to do what I can as time permits.

I do not neccessarily need devfs - but udev lacks two features I need and I do not see any way to add them without creatign the same sort of problems as devfs has.

>> Devfs can do this, but it is not necessarily a good thing.
>> I tried it - and it only works if someone tries to look up
>> a particluar name, such as /dev/dsp. It doesn't work when someone
>> does a "ls /dev" to see what devices is there.
>> A "ls /dev/dsp*" didn't find the multiple soundcards for which
>> modules weren't yet loaded.
>

no way. this requires far deeper devfs integration that is currently available. there was code that did it for removable media; it was removed during 2.5 series. fixing bugs in devfs is one thing; reintegrating it into kernel is another.

basically devfs in 2.6 is reduced to

mknod from within drivers
devfsd notification on lookup

> Nor would you want it to... Although, it might be handy for something
> like a SCSI controller. An opendir() in its directory would trigger the
> kernel to see what's attached to it. Postponing the probing of every LUN
> until someone goes looking could speed up boot times quite a bit.

I must admit I never used devfs names myself so it proved rather useless to me even in 2.4 times.

-andrey