On Fri, 31 Dec 1999, Chuck Robey wrote:
> On Fri, 31 Dec 1999, Brian Fundakowski Feldman wrote:
>
> > The way certain devices, like cd with its monotonically increasing counter
> > where devices are probed in order and assigned device based on precedence
> > and not hardwiring/controller connection, work is consistent between
> > the kernel and MAKEDEV. If you have 2 cd devices, you have cd0 and cd1,
> > so MAKEDEV accepts "cd2" for "two cd devices". All CD devices work
> > that way. Disks don't, because there is potential for hard-wiring
> > there, and will often be gaps.
>
> Why are "certain" devices wildly different than all other ones? I've
> never encountered that kind of syntax before, and I can't see that it's
> documented anywhere at all. Certainly, MAKEDEV itself (in it's
> comments) treats cd* just like all the others, specifying that the number
> following is a unit number, and *not* a quantity. I don't know when this
> happened, but it's surely not obvious. Not one word in the handbook,
> either.
*shrug* This is the only rationality I could think of. Obviously, this
breaks POLA, so it should be changed (with ample warning).
>
> In fact, according to cd(4), you *can* specify the unit number:
>
> ... Prior to FreeBSD
> 2.1, the first device found will be attached as cd0 the next, cd1, etc.
> Beginning in FreeBSD 2.1 it is possible to specify what cd unit a device
> should come on line as; refer to scsi(4) for details on kernel configura-
> tion.
>
> That makes this odd setup even odder. Can't understand why this was done.
So maybe it's just hysterical raisins. I'm not saying I like the behavior,
just that I understand what that MAKEDEV behavior is.
>
> ----------------------------------------------------------------------------
> Chuck Robey | Interests include C & Java programming,
> New Year's Resolution: I | electronics, communications, and
> will not sphroxify gullible| signal processing.
> people into looking up | I run picnic.mat.net: FreeBSD-current(i386) and
> fictitious words in the | jaunt.mat.net : FreeBSD-current(Alpha)|
> dictionary. |
> ----------------------------------------------------------------------------
>
--
Brian Fundakowski Feldman \ FreeBSD: The Power to Serve! /
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