scant description for devfs - unable to create /dev/ad3* or use disklabel

[Lowell Gilbert]

ecsd <ecsd at ecsd.com> writes:

> The transition to using devfs versus MAKEDEV is not very well documented,
> and I find no way to create /dev/ad3-anything although I have a /dev/ad3
> and have used "disklabel -w -r ad3 auto" to initialize it.
> 
> I wish there were an example section for devfs(8) that showed how to use
> devfs to do what MAKEDEV used to do. I have seen the remark "devfs
> will create the node for you", but "disklabel -e /dev/ad3d" and
> "disklabel -e /dev/ad3s1d"
> fail "no such device" whereas "disklabel -e /dev/ad3" reports
> "operation not supported
> by device". Perhaps I could use mknod, but I don't know what minor
> numbers to
> use and doing "file ad*" doesn't show a clear pattern of assignment.
> 
> I wish MAKEDEV were not removed, as it is an easy, well-known interface
> to creating device nodes - as opposed to the opaque devfs, inasmuch
> as, if I had
> MAKEDEV I would be done by now whereas there is nothing in the FAQs,
> nothing in the search, and nothing in the release notes that describes
> the devfs
> replacement for this common operation. Now I am left guessing whether I'll
> have to reboot the system to see the partitions on /dev/ad3. MAKEDEV would
> just work with no fuss.

Those are just the breaks of using a "technology preview" release.
The documentation is coming along, and should be pretty solid by the
time 5.x is ready to be recommended for production use.

I don't think you understand how device nodes work; they're not
magic, and don't add devices into the kernel.  If devfs doesn't create
them automatically, building them wouldn't do any good, because the
device numbers wouldn't be understood by the kernel.