Re: Fixing, reestoring DEC FDDI (DEFPA/DEFEA/DEFTA/DEFQA) in 8.2, 9.2; restore to -current?

[Jason Thorpe <thorpej%me.com@localhost>]

> On Feb 11, 2024, at 1:29 PM, Jonathan Stone <kiwi_jonathan%yahoo.com@localhost> wrote:

> Turns out  that  fddi_ifattach() is broken in 8.2 and 9.2.  It never initialises sc_ec.ec_lock, which causes a panic the fisrt time the kernel tries to add a multicast address to the interface.  If you're using IPv6 (I don't; I comment out "options INET6"),  the panic occurs soon after boot when ipv6 discovery starts.

^^^
Important context.

> I would like to restore "pdq" (fpa, fea, fta, whatever a qbus attachment is; or write one if none) to -current.
> However, 10_RC4. doesn't even have if_fddisubr.c. 

Right, it was removed from -current before netbsd-10 branched after some discussion.  Same with Token Ring, for the same reason ... a bunch of apparently unused code that had no work done to make MP-safe improvements like the Ethernet code received, and the work hadn't been done because, well, no one was apparently using it.  Looks like I was right, because (a) no one screamed when it disappeared, and (b) when someone tried an older version that was still around, it blew up in their face. :-)  Anyway, having that unmaintained code lying about introduces a practical barrier to making further improvements to the networking code, especially when those improvements introduce changes to the contracts between the layers.  In the case of the FDDI code, there's the additional complication that the PDQ driver is ... well, it's something!  Namely, a maze of twisty #ifdefs, all alike, where you stand a very good chance of being eaten by a grue.

> I don;t want to re-create the hack of having two different initialisers for the IEE 802 (sic) [*] portions of "struct ethercom'.
> A cleaner solution is to declare a new struct with all the members of 'struct ethercom', except the  'struct  ifnet ec_if;
> 'struct ethercom' then becomes a struct with two members: a struct ifnet, and the new struct (struct iee802_common?).
> That allows clean separation of code which manipulates the additions in today's "struct ethercom', from code which also manipulates struct ifnet.
> 
> Thoughts?  Anyone actively against  PR'ing and (hopefully) minimal patches NetBSD-8 and NetBSD-9?
> Or against restoring FDDI to -current. (and perhaps backporting to NetBSD-10)?
> If I have to, I can probably ship a pair of DEFTAs to an interested contributor, if support from me is too tenuous.
> 
> [*] FDDI is not IEEE 802. But it's derived from Token Ring,, 802.5, which is. And I suppose the refactoring I'm proposing here could add supporing Token Ring, if anyone actively wanted to...

See also about Token Ring above :-)

I am not at all opposed to resurrecting this stuff, doing a re-factor to make it easier to maintain going forward, etc.  If someone wants to volunteer to do that work (and then actually DO it), who am I to say no?  After all, I love obsolete technology as much as (and quite possibly more than) the next guy!  *Stares in 6800.*  But I would prefer we not return to the previous state where the code went completely unmaintained and unused.

-- thorpej