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



On 9/16/2018 2:27 AM, Michael van Elst wrote:
netbsd-embedded%gmx.com@localhost (Don NetBSD) writes:

Ah!  So, the sd(4) driver won't pass "non-scsi" commands and
the sd(4) devices might not accept scsi commands.  (damned if you
do, damned if you don't)?

The sd driver just passes some byte sequence, some are intercepted by
mfi, some aren't. The mfi firmware might do more before it actually
reaches the disk.

The 2950 uses an mpt(4) -- though I suspect your points apply equally.

I'd have to make sure I numbered the targets on each scsibus as well.

Yes, you need to wire scsibus (if there could be more than one) and
you need to wire sd.

So, my kernel config should contain N+1 sd entries (the N+1th for a
wildcarded "sd?") each with specific unit numbers.  Ditto scsibus(4)'s
as well as the controller (mpt) to which they attach.  In this way, I
should be able to rely on the /dev mappings to specific hardware (even
in the absence of said hardware or portions thereof).

Yes, that's what I'm trying to guard against.  I can almost guarantee
that someone will get the "bright idea" that they can hack together a
second appliance -- using DIFFERENT hardware (a computer is a computer,
right?) and just cloning the system disk.  Then, complain when it
doesn't work as expected.

You need to wire down scsibus to a specific controller. I.e. adding
another controller or replacing it with a different model makes your
kernel config void.

That's acceptable -- it's an *appliance*, not a "general purpose computer".
I just need to ensure that the software either knows that the configuration
has been changed (and can complain about it) *or* lock the system (hardware
and software) so it *can't* be changed.

(sigh)  This would be *so* much easier if I just pulled product off the Line
and tweeked the firmware!  "Want another?  Go get one (and *I* know it will
be identical to the last!)"


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