Re: Sizing hardware drive capabilities (in the absence of probed devices)

[David Brownlee <abs%absd.org@localhost>]

On Mon, 24 Sep 2018 at 11:08, Don NetBSD <netbsd-embedded%gmx.com@localhost> wrote:
>
> On 9/18/2018 3:54 AM, David Brownlee wrote:
> > Just some musing about handling drive mappings:
> >
> > For sd devices you could use "scsictl sdX identify" to map back from
> > sdX to (scsibus, target, lun) numbers and then onto each drive's
> > physical location.
>
> OK.  That would help me initially identify the "slots" in order to
> hard-wire them in the kernel.  I.e., stuff every slot, boot, then
> "identify" each disk (having made the contents of each disk unique
> enough to map to the probed devices).
>
> Presumably, once each slot is wired down, then it need not be
> populated at boot -- yet the device will still exist for it when it
> later "appears".

Yes, though if you can identify the slots for hardwiring into the
kernel you could also run the same process at runtime as run a GENERIC
kernel.

I have no idea whether this would actually map to your real
requirements, but a possible workflow could be:

Bringing up new appliance ("slot mapping")
- Assuming you have "ID" devices digitally and physically labelled 1..n.
- User is directed to insert as many ID devices as they have slots
switch on machine
- Appliance boots, detects it has devices attached, checks to see they
are ID devices, updates slots and records its slot mappings

Normal use
- When a new sdX or wdX device is detected system determines its slot
mapping and uses it when talking to user
- If it can't determine slot mapping, it suggests a new slot mapping
pass (something strange has happened)

Optional extra credit ("Where is what slot")
- User is instructed to apply sticky number labels next to ID devices
when bring up appliance

Optional extra credit ("Where is what slot and sticky labels fall off")
- User directed to take photo of appliance with ID devices to record
where the slots were & upload to web server on applicance
- If user is confused on slot mapping web server on appliance can show
mapping picture

Optional extra credit ("Users mess with hardware/swap disks to other machines")
- At boot time system takes a copy of dmesg and notes the available
atabus/scsibus and device names
- If this ever changes it forces a new slot mapping pass

David