From owner-freebsd-arch  Thu Nov 29  7:57:42 2001
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From: "Jeroen C. van Gelderen" <jeroen@vangelderen.org>
To: "'Poul-Henning Kamp'" <phk@critter.freebsd.dk>,
	"'Robert Watson'" <rwatson@FreeBSD.ORG>
Cc: "'Josef Karthauser'" <joe@tao.org.uk>,
	"'Garrett Wollman'" <wollman@khavrinen.lcs.mit.edu>,
	<mjacob@feral.com>, <arch@FreeBSD.ORG>
Subject: RE: Anybody working on devd? 
Date: Thu, 29 Nov 2001 11:57:27 -0400
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>And where do you want to run the devd for jails ?  Inside the 
> jail ?

I assumed that Robert was aiming at a single devd for the whole
system. Here is how I imagined it would work:

There seems to be a parent-child relationship between the host
and the various jail devfs instances. The devfs instance in a 
jail contains a subset of the nodes in the host (parent) devfs.

Now if each jail devfs has as a parent the hosts devfs and the
host is its own parent, we have each devfs instance put a control
node (/dev/devfsctl) in its parent. Thus the host devfs would 
end up containing a series of /dev/devfsctl* nodes controlling 
all devfs instances on the machine and a single devd would open
those and control every devfs.

Each devfs would have a local /dev/devfsevent node that clients 
can listen to to be notified about device arrival and removal.

Another thought was that each jail devfs could show up in a
directory on the main devfs:

/dev/ad0s1a
/dev/ad0s1c
/dev/ad0s1e
/dev/ttya
/dev/ttyb
/dev/jail0/ttyb
/dev/jail0/ad0s1e
/dev/jail1/ttyb

This would in fact allow for easy management of the jail devfs.
Maybe the jails could be controlled with a device node as well:

/dev/jail0.ctl
/dev/jail0/ttyb
/dev/jail0/ad0s1e
/dev/jail1.ctl
/dev/jail1/ttyb

Whether this is possible or not I don't know. But it is what I
imagined from Robert's mails...

Cheers,
Jeroen


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