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Re: (Semi-random) thoughts on device tree structure and devfs

On Wed, 10 Mar 2010 11:53:43 +0900
Masao Uebayashi <> wrote:

[device node ownership and modes on devfs]
> Is it acceptable for you to do such things by some layering?
Anything else but "chown jkunz.users /dev/ttyU0" is awkward to me.
So what ever solution for this problem is introduced (udevd,
rc.script, ...), I have to learn a special way to configure device
node ownership and modes on devfs.

There could be some devd(8), that listens for ownership and modes
on devfs and stores it on disk. At next boot it could reconstruct
ownership and modes. But this looks a bit fragile to me.

> > The Linux devfs solved this problem with an init-script, that changed
> > ownership and modes after each reboot. Looked a bit awkward to me when
> > I had to deal with it.
> A bit?  I thought udevfs's config file is totally inacceptable for
> missiong critical embedded purposes.  Why do we have to learn a new
> syntax to configure only a few device file permissions?
I talked about the long gone Linux devfs, not udev. But it doesn't
matter. Anything else then chmod(1) and chown(8) needs to be learned.
So it doesn't matter what new stuff I have to learn to get it done.

BTW: My dayjob is to programm an embedded system running Linux.
A (small) part of my work is to fight with udevd. And those systems
are used in mission critical applications.



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