HEADSUP: Change of makedev() semantics.

[Poul-Henning Kamp]

I am in the process of adding ref-counting and locking to dev_t,
and would very much prefer if we could get this step completed
soon before 5-STABLE gets branched.

All this will be transparent to the majority of device drivers, as
the refcounting will happen in the make_dev() and destroy_dev()
family of calls and normal drivers need not know more about it.

But there are a few remaining users of makedev() which get in the
way of this effort, and we must get these fixed.

Basically:

	1. Do not call makedev().

	2. If you do cloning, please look at the patches I posted
	    for if_tun/if_tap for how to do it.

	3. If you do a "normal" device driver, cache the result
	   from when you call make_dev().

	4. If you translate "foreign dev_t's", ie emulators or
	   compat code, contact me.  I'm not sure I understand
	   how this works and should work and we need to talk.

	5. If anything else or in doubt, ask me.

Can I see some volounteers and/or maintainers please ?

	./alpha/osf1/osf1_misc.c
		badly named local macro ?

	./compat/linux/linux_stats.c
	./compat/svr4/svr4_types.h
		compat code, not sure that this is correct now.
		Must be supported by new "finddev" semantics.

	./dev/ata/atapi-cd.c
		cloning related to root mount.
		gets fixed when phk GEOMify the driver.

	./dev/sound/midi/midi.h
		Not sure.

	./dev/nmdm/nmdm.c
		pseudo-cloning.  Should do real cloning.

	./dev/syscons/syscons.c
		Related to console initialization.  Maybe tricky.

	./dev/sound/pcm/dsp.c
	./dev/sound/pcm/mixer.c
	./dev/usb/ugen.c
	./dev/usb/uscanner.c
		Failure to cache result of make_dev()

	./dev/vinum
		Failure to cache result of make_dev() ?

Thanks in advance!

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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