Date: Mon, 31 Aug 2015 13:02:11 +0300 From: Daniel Braniss <danny@cs.huji.ac.il> To: hackers@freebsd.org Subject: Re: Puzzle involving serial console and ...??!? Message-ID: <C51443EA-C32C-445C-B9BF-84CE4A3FC9D7@cs.huji.ac.il> In-Reply-To: <20150831030639.GH1153@albert.catwhisker.org> References: <20150831030639.GH1153@albert.catwhisker.org>
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> On Aug 31, 2015, at 6:06 AM, David Wolfskill <david@catwhisker.org> = wrote: >=20 > I may be going mad -- that's likely the simplest explanation, and > Occam's Razor would thus indicate that this hypothesis should be > accorded a degree of plausibility, at least. >=20 > As described in = <http://www.catwhisker.org/~david/FreeBSD/upgrade.html>, > I have my own quirky ways of upgrading FreeBSD systems, the basics > of which remain fundamentally unchanged for the last dozen years > (well, a few more than that, but...). In turn, much of that approach > was borrowed from one of my pre-FreeBSD experiences in an IBM > mainframe environment (as a "systems programmer"). >=20 > What's causing me to question my tenuous grasp of reality is this: > Referencing the above-cited Web page, my build machine ("freebeast") > normally runs headless, and I use a cable to connect its serial > port to the serial port of one of my other machines ("albert"). >=20 > By doing so, I have a working serial console (once the FreeBSD > loader gains control from the BIOS, at least)... half the time. >=20 > I have determined that whether or not I have a functioning serial > console for freebeast depends on whether I boot albert from slice > 1 or slice 2: if from slice 1, it doesn't work; if from slice 2, > it does. >=20 > Even when the contents of the 2 slices are functionally equivalent > (that is, the file systems of the 2 slices are as "the same" as a > "dump 0Lf | restore" pipeline can make them, except for a deliberate > difference in the contents of /etc/fstab (as the root and /usr file > systems are on different slices in the two cases)). >=20 > I use tip(1) on albert to access the serial port (as I have since > 1998); I leave the speed at the default of 9600 because it has -- > save for this case -- always worked for me in the past. >=20 > Does anyone have any suggestions for figuring out what is really > going on here? While I can't just reboot "albert," I have another > (similar) machine ("pogo") that I use for testing stuff that I plan > to do to albert, and I could easily connect teh serial cable to > pogo instead of albert and tinker with that. >=20 the simplest way to check the serial, use a paper clip, and jump 2 & 3, this will loop the xmit to the receiver, and thus make sure that at least albert side is ok, no matter the baud rate. newer freebsd have changed the way the serial port is treated! We use com2 for the serial (also for serial over lan) and every new version I have to go through many loops till all is working again. > Thanks. I'm on the list, so list replies need not Cc: me. >=20 > Peace, > david > --=20 > David H. Wolfskill david@catwhisker.org > Those who would murder in the name of God or prophet are blasphemous = cowards. >=20 > See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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