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Date:      Sat, 29 Feb 2020 13:57:19 -0700
From:      Warner Losh <imp@bsdimp.com>
To:        Ed Maste <emaste@freebsd.org>
Cc:        freebsd-stable stable <freebsd-stable@freebsd.org>
Subject:   Re: Any sync-serial driver users (ce/cp/ctau/cx)?
Message-ID:  <CANCZdfpereGF0OKD2cRPhP=CF8DhtT0eyM3c1J4Z0wnry8uBUQ@mail.gmail.com>
In-Reply-To: <CAPyFy2Bmj5VuMgNdp4oKaag%2BHWW6Gfj17MXPdBFZbdTL8riyXQ@mail.gmail.com>
References:  <CAPyFy2Bmj5VuMgNdp4oKaag%2BHWW6Gfj17MXPdBFZbdTL8riyXQ@mail.gmail.com>

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On Sat, Feb 29, 2020, 1:18 PM Ed Maste <emaste@freebsd.org> wrote:

> Is anyone using sync serial drivers ce, cp, ctau, or cx? NYCBUG's
> dmesg didn't turn up any entries. I suspect these are obsolete and
> ought to be removed.
>

These date from the 2000s. They were important for point to point links
until maybe 2000 and largely obsolete by 2010 or so as internet connection
technologies shifted away from sync T1/E1 lines to other technologies...
These drivers replaced earlier ISA versions of the cards, see
sys/i386/isa/cronyx.c for driver that also supported MSDOS! through at
least stable/3. the cx driver dates from this time. The others date from
later imports (2004-2006) by Roman Kurakin and are for the PCI generation
of cards.

Looking at the drivers themselves, we see that they haven't been updated,
except for API changes, since maybe 2005 or 2006. The code was made
MPSAFE at the time. However, several transitions in technology have
happened in the network and tty layers and it's not clear this code works
well with them. All the Giant code for network protocols and such was
removed in 2007. And several other major changes since then. The ce driver
has FreeBSD_version ifdefs from 3 to 7. None of the other drivers have such
support. All of these drivers have mechanically obfuscated C code to
implement their core functions (at least I hope it was done mechanically).

Roman was the maintainer through 2006 or 2007. I think it was then handed
off Murray Stokely around that time, then I think I got some number of
cards around 2010 from him. We've been looking for a maintainer for these
since then. There have been no takers. I'm unsure where these cards wound
up in my collection, to be honest, but if there's serious interest I can
look but I'm not hopeful I still have them as I've been purging all the
stuff older than 10-15 years from my collection recently...

Given the ~15 years of nothing but API changes to these cards, and the lack
of testing of those changes, and the large technology transitions in net
and tty layers of the system, I'd honestly be surprised if these drivers
still work.

Warner

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