ifmedia change (was Re: change ifmedia word from int to uint64_t)

[Masanobu SAITOH <msaitoh%execsw.org@localhost>]

(I changed the Subject)

 Hi, all.

I'm working to overhaul ifmedia(4) and the lower layer. Changing the
ifmedia word from int to uint64_t was one of them. If I commit it to
current and then netbsd-9 is branched, Other changes will be added
to -current in future. It will make the ABI change twice. It makes
the compat code in if.c and ifmedia.c very complex and also makes
some 3rd party programs complex.

So,  I gave up to change the ifmedia word from int to uint64_t. Instead
of it, I'd like to change the ifmedia word not changing the size but
changing the usage usage only on IFM_ETHER.

 Diff:
	http://www.netbsd.org/~msaitoh/ifmedia-20190513-0.dif

The strategy is almost the same as FreeBSD. Many bits of IFM_OMASK
for Ethernet have not used, some of them are used. The differences against
FreeBSD are:

 - We use NetBSD style compat code. Don't use SIOCGIFXMEDIA.
   The old ioctls are prefixed with 'O'.
 - New IFM_ETH_XTYPE's bit location in FreeBSD is little strange.
   We use from bit 13 to 15.
 - FreeBSD changed the meaning of IFM_TYPE_MATCH(). I think we should
   not do it. We keep it not changing and added new IFM_TYPE_SUBTYPE_MATCH()
   macro for matching both TYPE and SUBTYPE.
 - Added up to 400GBASE-SR16.

The above diff includes a test patch in if_tap.c. I tested the
following environment on the new kernel:

 - New amd64 dynamic link ifconfig(8)
 - netbsd-8 amd64 dynamic link ifconfig(8)
 - netbsd-7 i386 static link ifconfig(8)
 - netbsd-4 amd64 dynamic link ifconfig(8) (for COMPAT_43 testing)


I think this change isn't harmful, so I'll commit the change in
this weekend if no one objects. Feedback are welcomed.

 Thanks in advance.

-- 
-----------------------------------------------
                SAITOH Masanobu (msaitoh%execsw.org@localhost
                                 msaitoh%netbsd.org@localhost)