Date: Fri, 31 Dec 1999 09:25:42 -0500 (EST) From: Brian Fundakowski Feldman <green@FreeBSD.org> To: Chuck Robey <chuckr@picnic.mat.net> Cc: FreeBSD-current@FreeBSD.org Subject: Re: multiple cd devices Message-ID: <Pine.BSF.4.10.9912310922230.4996-100000@green.dyndns.org> In-Reply-To: <Pine.BSF.4.21.9912310152050.2014-100000@picnic.mat.net>
next in thread | previous in thread | raw e-mail | index | archive | help
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! / green@FreeBSD.org `------------------------------' To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.10.9912310922230.4996-100000>