Re: New-bus unit wiring via hints..

> From: Marcel Moolenaar <xcllnt_at_mac.com>
> Date: Sat, 27 Oct 2007 12:09:29 -0700
> Sender: owner-freebsd-current_at_freebsd.org
> 
> 
> On Oct 27, 2007, at 10:58 AM, John-Mark Gurney wrote:
> 
> > Yeh, you're solution was to simply declare that anyone who knows that
> > COM1 is at 0x3f8 is wrong, and to use a different, yet again arbitrary
> > solution which is which is listed first in ACPI...
> 
> Exactly. Anyone who "knows" that COM1 is at 0x3f8 while
> the computer right in front of them clearly states that
> COM1 is at 0x2f8 is in denial.
> 
> > So, if one ACPI implementation puts _UID = 0 at 0x3f8, but lists it
> > after _UID = 1 at 0x2f8, that it's fine for sio0 to be _UID = 1?
> 
> Yes. sio0 is nothing more than the first serial port found during
> enumeration.
> 
> 
> > So, why are you continuing to argue about a simple thing that you  
> > on your
> > machines can simply remove the hints?
> 
> The ability to wire is good. Implementing it right
> is important.
> 
> >  What are your technical arguments
> > for mandating a different, non-historical, based arbitrary selection?
> 
> I'm not mandating anything. I'm merely pointing out how
> reality has changed and that it's important to adapt,
> adopt and improve...
> 
> Where are your technical arguments, putting aside the
> mere technically of the statement that you consider
> yourself an old fart?

"Reality has changed"? Yes, it has, at least a bit, but not to the
point where we want to confuse serial ports.

Back in the days of v3 and v4, adding an IDE disk to a system could
cause existing drives to change their device names. This meant that the
fstab was unexpectedly wrong and things sometimes got messy. The option
to fix this was added in V4 and moved to GENERIC after a while. Now the
order in which IDE ports is scanned does not break the device names.

If I update my BIOS, the port marked '1' on the back of my system should
not abruptly change from sio0 to sio1. (Or, because some kernel change
does this.)  If I have a system with scripts to talk to a device on a
given port, I would be very annoyed if it suddenly changed.

In my case, I am only talking to a data logger and not actually
controlling something, but I should not have to worry about having a port
name change or finding that _UID1 was no longer the same device if I
move to a new mother board.

COM1 (or whatever you choose to call it) has been at 0x3f8 since at
least the IBM-AT and probably was there in the IBM-PC back at the dawn
of time. (Yes, I had been working with computers for several years
before then and I suspect many of the others in this discussion had
been, too.) Please don't break it! Talk about POLA!
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman_at_es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751