using swap on a separate slice

[walt]

Ja'far Railton wrote:
> On Tue, Dec 19, 2006 at 11:23:28AM -0800, walt wrote:

>> If the existing swap partition in linux was e.g. /dev/hda7, then in
>> DragonFly you would do this:
>>
>> # cd /dev
>> # ./MAKEDEV ad0s7

> Thanks for the replies. 
> 
> Well, I tried MAKEDEV with ad0s4 (and other permutations as I had
> been playing around with fdisk, marking the slice 'swap', then 'unused',
> so I thought is might show up ad0s3x or even ad0s5x).
> 
> Nothing would swapon. I got 'Device not configured' or 'invalid
> argument' depending on the /dev (e.g. /dev/ad0s4, ad0s4{a,b}, etc.).

Computers are truly too complicated -- a veritable Tower of Babel.

The first thing that strikes me about your reply is that ad0s4 is
*not* an extended partition, so this may be the underlying problem.

Primary partitions are numbered 1 to 4 (not 0 to 3 as any computer
nerd might reasonably expect).

Any one of those four primary partitions can be sub-divided into
'extended' partitions, and very often partition 4 turns out to be
the one that gets elected.  (No, not always, you silly!)

Extended partitions are numbered starting with 5 because 1-4 are
already taken by the primary partitions.  Yes, even if your disk
has only a single primary partition, numbered '1'.  (2 thru 4 are
still reserved, even if they don't actually exist.)

My uninformed impression is that all of this insanity is peculiar
to the IBM-PC/Intel architecture.  Does anyone here know if the
remainder of the computer universe is similarly afflicted?