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Subjectserial8250 madness
Is anyone active in the serial code?

I thought I would make some in-house servers send output via ttyS0 from
grub, kernel boot and console, like our rented remote servers do. I set
it all up and basically nothing worked properly, so I started
investigating with a null modem cable, setserial and cu to see what was
happening.

Machine A

ttyS0 works fine. Can get grub output, kernel boot and console via ttyS0
as I wanted.
ttyS1 doesn't work at all. It's detected, enabled in the bios etc etc
but just doesn't work at all.

Machine B

ttyS0 and ttyS1 will both receive, but neither will send. Go figure.
Tested using a null modem cable, setserial and cu against the known good
machine above.

Machine C

Grub and kernel outputs fine during boot, right up til the serial8250
output appears in the kernel log, at which point it then prints 'LSR
safety check engaged' and reboots.
Tried again without the console=ttyS0,57600 kernel parameter and it
boots OK but starts printing the 'LSR...' message again as soon as
agetty tries to attach to ttyS0. Doesn't reboot though...

The Machines are all amd64, various motherboards, identical distros
using 2.6.28.1 kernel.
Either I have a particularly motley collection of kit, or the serial
code is in a pretty bad way.

I can provide further info/testing if anyone is active/interested.

Andrew Walrond



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