Subject: Re: devfs, was Re: ptyfs fully working now...
To: Bill Studenmund <wrstuden@NetBSD.org>
From: Matthew Orgass <firstname.lastname@example.org>
Date: 12/01/2004 08:45:52
On 2004-12-01 email@example.com wrote:
> > > * I think the idea of "locator" names needs more thought, or at least
> > > more description. Multiple namespaces raises the possiblity of
> > > different names for different means of reference (device file, kernel
> > > printed message, sysctl node, ifconfig -a type stuff, etc.), and
> > > trying to determine what name is appropriate where and matches what
> > > other name(s) could become an easy source of error and confusion. I
> > > haven't noticed any suggested details about how this would work in
> > > this thread.
> > The only locator namespace I've had in mind, and the only one I've
> > understood other folks have had in mind, is that of kernel devices. i.e.
> > config locators, the things you can put in kernel config files.
> I was a little confused about locators, but not too much (read the first
> sentance as WRT devfs). Devices can have more than one locator, so what I
> am most concerned about here is that no part of the kernel refer to a
> device without also referring to the cannonical name.
But I was still confused, of course. I think there are essentially two
methods of reference, cannonical id and unique id, which could further be
restricted by parent's cannonical name. That shouldn't be too hard to
keep track of.
Also, my idea of reference counting is an obvious DOS possibility.
Blessing the device before it appears for dynamic permissions correction
would work, plus provide an instance id for comparison. A separate means
for the admin to specify "don't put a new device here until I say you can"
for safe manual modification could also potentially be provided.