[GTALUG] war story: keyboard failure leads to sustained mayhem

D. Hugh Redelmeier hugh at mimosa.com
Mon Jul 6 14:37:40 UTC 2015


| From: James Knott <james.knott at rogers.com>

| On 07/06/2015 09:10 AM, Kevin Cozens wrote:
| > On 15-07-05 10:59 PM, D. Hugh Redelmeier wrote:
| >> - apparently I really only use the KVM for booting; it would be
| >>    nice if PCs had been designed to be happy headless
| >
| > In older days (a few generations of PC ago) there used to be a BIOS
| > setting where you could tell it to ignore keyboard errors.

| I have 4 computers here, one with a year old motherboard.  3 of them can
| run headless and the other, an old Compaq, I just leave an old keyboard
| plugged in, but still access it via KVM.

Before I got a PC, I had Sun workstations.  They were willing to talk
via a serial port to a "console" (they could use a display and
keyboard too).  This let you do things like reboot when hung, watch
all the exciting messages during booting, configure the machine, run
hardware diagnostics, etc.

I don't really want to lose those functions.  On PCs, they seem to
require a console (or some quite expensive "management" features).
That's why I use a KVM (and grumble).

I think that the expensive management functions use ethernet
transport.  For security, it ought to be separate from other networks.
I have no experience with them.  Unfortuately, I think that the
protocols are proprietary and different for each brand of computer.

KVMs are either expensive or deficient.  Or both.

- cheap ones only support VGA, a very obsolete standard

- some cheap KVMs don't pass DDC info so the OS cannot determine
  characteristics of the monitor.  This causes a variety of problems
  (some modern Linux distros won't work out of the box with this).

- some better cheap KVMs pass DDC information, but only to the
  computer currently selected.  This works badly after a power failure
  when each computer is rebooting at the same time.

- there are issues (that I don't understand) about keyboard and mouse
  states carrying over on switching.

- I have another KVM that is normally sold for ~$500 that does a lot
  right: support dual-link DVI, does pass DDC to all computers.  I
  paid $100, so that was a great choice.  Even so, it gets a bit
  confused by some mice.

HDMI switches are quite cheap these days.  That would handle the V
part of KVM.  Maybe the clutter of multiple keyboards and mice would
be OK.  HDMI includes an ethernet signal now.  Someone should build a
pair of dongles to ship K and M stuff over that channel.  USB over
ethernet is probably already a thing.


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