i386/100831: sio ignores BIOS information about serial ports - bounty offered

[Marcel Moolenaar]

The following reply was made to PR i386/100831; it has been noted by GNATS.

From: Marcel Moolenaar <marcel at xcllnt.net>
To: Warner Losh <imp at bsdimp.com>
Cc: nate at root.org, jrhett at svcolo.com, freebsd-gnats-submit at freebsd.org,
        freebsd-i386 at freebsd.org
Subject: Re: i386/100831: sio ignores BIOS information about serial ports - bounty offered
Date: Thu, 3 Aug 2006 15:16:22 -0700

 On Aug 3, 2006, at 2:28 PM, Warner Losh wrote:
 
 > Agreed.  However, the sio flags to designate a unit as console is the
 > only thing that doesn't fit well with hints, as presently implemented.
 > It should really be something like: console.type={serial,video}
 > console.location=<io=xxx,mem=yyy>
 >
 > so that would could use a video card not mapped to the default address
 > as the console, etc.  It would be up to the driver at attach time to
 > look at the available console meta-information to see if this driver
 > matches that information.  Then it wouldn't matter for a serial
 > console point of view what driver unit is assigned.  It might matter
 > for other reasons...
 
 This is exactly what I implemented for uart(4). As long as the I/O
 location used by the low-level console is actually being "found"
 during bus-enumeration and the right driver is being attached,
 then you always have a working console for going to single-user
 mode. Not to mention that the firmware typically exports console
 information in terms of I/O location (see DIG64 HCDP or Microsoft
 SPCR), so you can trivially use that too (see for a real example
 src/sys/dev/uart/uart_cpu_ia64.c).
 
 -- 
   Marcel Moolenaar         USPA: A-39004          marcel at xcllnt.net