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.
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.
>
>
----------------------------------------------------------------------------
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. |
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