Re: RS232 consoles (was Re: NetBSD-7.0 boots OK and NetBSD-8.0 hangs/crashes during boot on a MacBook7,1)

[Steve Rikli <sr%genyosha.net@localhost>]

On Mon, Jul 27, 2020 at 02:53:13PM -0700, Aaron J. Grier wrote:
> On Mon, Jul 06, 2020 at 10:07:37AM -0700, Steve Rikli wrote:
> 
> The reference server motherboards for Grantley (Haswell / Broadwell
> Xeon) and the later Purley (Icelake / Cascade Lake) I've worked with
> moved from DE9 to RJ45 for serial, so Intel-branded (and Intel OEM'd
> systems) do have this.  I can't recall if it follows the cisco standard,
> though.

When you say "server" does that include sub-ATX units as well, e.g. ITX
and smaller?  I'd take that as good news.

I realize the thread (including my own anecdotes) branched off to rackmount
gear, but I think we were also talking about serial console on laptops,
small systems, and presumably desktops, embedded, etc.  ITX has been my
go-to for small home servers, I assume I'm hardly unique there, and I've
also discovered some very nice even smaller systems (e.g. Qotom) with
entirely useful serial ports. It'd be great to see NUC's do likewise.

> IPMI defines serial-over-LAN which mostly works, and some BMCs implement
> ssh to serial, which is better.  there's typically no need to touch the
> GUI or a web interface at all, although resolution of the chicken-and-
> egg configuration seems to be very vendor-specific.  (out-of-box boots OS over
> PXE and configures BMC over IPMI/KCS?  out-of-box BMC does DHCP and
> fetches initial configuration from returned DHCP parameters?  etc...)

I've not cared for SoL on the rackmount servers we use at $work, but that
could be the vendors' implementation, or equally likely our configuration.

Wrt chicken-egg, I'm not terribly bothered by initial setup being done
from a VGA+keyboard crash cart or similar.  We don't run at google-scale
at work (and I certainly don't at home) so spending a little setup time
in BIOS once out of the box is okay for us. I do appreciate it when vendors
put mac addresses for BMC (if there is one) and onboard NIC somewhere on
the chassis, though.

> Serial console redirection is definitely provided as part of the BIOS
> reference code provided by Intel, although the IBVs seem to butcher
> features as part of their "value-add" process.

I wish more vendors included serial console redirection, but sadly it
seems more likely that serial ports aren't included at all, particularly
for desktop or small systems a home user might buy these days.

> there seems to be a fundamental assumption on PC-based hardware (even
> modern generation) that a VGA adapter is necessary to the point where
> server BMCs implement a x4 PCIe endpoint for a VGA controller.  I've
> been working for Intel for over a decade now and I still don't get it,
> but maybe there are outside designs (facebook?) which omit this.

No argument here.  I miss Suns and SGIs and DECs et al which ran fine
with no graphics hardware installed.  Knowing that you were going to
get some kind of POST and boot output over the serial port was nice.
Different era.  :-)