Subject: Re: representation of persistent device status, was Re: devfs, was Re: ptyfs...
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Bill Studenmund <>
List: tech-kern
Date: 11/19/2004 14:48:02
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On Thu, Nov 18, 2004 at 10:15:37PM -0500, der Mouse wrote:
> > On the issue of namespaces, in one view of a "full devfs", even
> > having major,minor numbers as a namespace at all should go away, or
> > at least become a historical distraction.  The device *is* the vnode
> > in the devfs.
> I think that would be a mistake.  I've too often had occasion to have
> device files in unusual places in the filesystem.  (Not all that often,
> but often enough - maybe a half-dozen times in the two-plus decades
> I've been a sysadmin.)  Some of those could be handled with multiple
> mounts of devfs, but some couldn't really.  I think it would be a major
> step backwards to lose the ability.

Well, the main goal for devfs is to make major and minor numbers be=20
transient. So there's no way that old-style nodes in the fs will work.

However I think you're right that we need to be able to have more than=20
just /dev hold devices. chroot environments come to mind, and I'm sure=20
there are other uses. So we should figure in some sort of "slave mount"=20
devfs idea, so that we correctly deal with the idea of multiple device=20
vnodes for the same thing. I think making the "slave" mounts only list the=
devices they are configured to contain (like dev/zero, etc.) would be=20

Take care,


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