Re: Difficulty with netbooting - le0: lost carrier when bringing downthenetbsd kernel

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

Hi,

> I'm not really a new user to HP300; I used NetBSD on a few
> HP9000/340s pretty heavily a few decades ago.  I set up netbooting
> once way back for the experience/novelty, but pretty quickly
> figured out that running these machines diskless was pretty painful
> and SCSI disks were relatively plentiful.

Ah, got it. Welcome back to NetBSD/hp300!

> I was given this 360 many years ago (probably not a 362 as indicated
> earlier), but never put it to use and it sat in my closet (along with
> a stack of other hp300s) for many years.  But I'm building a computer
> museum in my office at work, and I've decided I want to get this
> machine running as representative of Unix minicomputers of the day.
> Also, it seemed like a fun project.

Indeed, keeping old hp300s (and other machines in the closet)
running the latest NetBSD has been a fun project for me, too ;-)

> Regarding carrier lost:
> 
> My 10base2 networking consists of a noname 10baseT hub connected
> via cat5 to the raspberry pi and a single 10base2 BNC port, a
> couple T's and terminators, and an approximately 1 meter long
> length of RG58.  And, of course, the 360 on one of the Ts.

I use a similar setup; a noname 10baseT hub with 10base2 BNC port
and RG58, to connect HP319 and other models with the System
Interface Boards.

> I checked the resistance on the terminators and, although they
> say 50 ohms, read out at about 30 & 38 ohms.  Not sure if that
> would be enough of a problem (also, do resistors decay over time?).

It can happen - old resistors can drift, especially if they have
seen moisture/humidity.

> I may have a spare system interface board I could swap in, in case
> it's the onboard ethernet that's causing a problem.  I can also
> check if there's an AUI port on either.

All of the System interface boards I have are only BNC,
but I'm not sure whether there were AUI variants.

> I looked to see if there were any direct 10base2 to 10baseT gadgets
> out there, and the answer is...no really.

A 10baseT hub with a 10base2 BNC is a reasonable approach, I think.

> Regarding my server setup:
> I see that you say that the kernel is delivered via nfs.  Does
> that mean there's no need for tftp at all?

You don't need TFTP for hp300 netboot. The boot ROM uses HP's RMP
and talks to rbootd(8) to fetch the NetBSD's boot program (SYS_UBOOT).
Then the loaded SYS_UBOOT uses BOOTP to get IP addresses, mounts the
NFS root directory indicated by BOOTP, and load the kernel from
there.

Some firmware on other workstations (certain Sun and SGI models)
use TFTP to load bootloader after rarp/bootparam or bootp,
but AFAICT most NetBSD's bootloaders use NFS to load a kernel
(because our machine independent standalone library for bootloaders
 just support both NFS and TFTP by default).

> Also. Regarding the network + nfs:
> I have an AUI port on my machine (in an expansion card), and when
> I use that rather than the I am able to successfully get to the
> point where it keeps asking over and over for the different netbsd
> kernels, over & over (as opposed to using thinnet, where it just
> hangs on the le0a carrier lost errors).  Can I use the AUI port to
> deliver the kernel (and the rest of the filesystem) via nfs?

If that AUI port is on a supported Ethernet interface (and the AUI
vs. thinnet selection is set correctly in hardware), it should work
the same way - SYS_UBOOT does't inherently require thinnet.

> ChatGPT claimed that the SYS_UBOOT bootstrap loader would only
> work on the thinnet network connection...but was it hallucinating
> on this?

AFAIK there is no software-configuable AUI/thin switch on hp300s.

All interfaces/models use hardware jumpers to switch them,
so software in SYS_UBOOT (and BOOT ROMs) don't get to choose
which physical port.

> As an aside, ChatGPT suggested that Version D ROMs would allow
> the bootloader to select other LAN interfaces.  Also, totally
> a hallucination?  I believe I have Version C ROMs, by the way.

I suspect ChatGPT is mixing up different bits of information
(e.g. "Boot ROM Revision B or later support network boot" and/or
old models that require system interface board don't have AUI ports,
and such models have such old revisions (C or prior)).

> Totally unrelated:
> I found in my stash a video board for which I have no idea what
> monitors it drives.  It's not a bunch of BNC connectors, but
> a 9-pin connector.  I don't have the model number on me right now,
> but when I looked for it on the intertubes I the only reference
> I could find referred to it as a monochrome graphics framebuffer.
> Does this right a bell for anyone?  I wonder if this is used to

I think it's A1096A monochrome Hyperion (1280x1024, 1 bit).
I also have the one (donated from Miod Vallat) and even X.org
1 bpp server should work on it (if your machine have enough RAMs):

 https://x.com/tsutsuii/status/1337987154555768832
 https://x.com/tsutsuii/status/1338007445252161538
 https://x.com/tsutsuii/status/1338023590902390785

It looks to use ordinary composite sync (like Sync on Green)
so even modern LCD with SoG support (including recent most DELL
LCD models; I'm using E1715S and P2314H etc.) can handle it.

> Thanks again,

No problem, thanks,
---
Izumi Tsutsui