[ale] Serial Port Qn

[Jeff Hubbs]

My primary system is a Gateway 2000 PCI-bus machine from early 1995 that came
with a 486DX2/66 and now has an Overdrive/100.  It is now set up as a dual-boot
Win95/Linux and I have recently been spending more time with it booted to Linux
because, well, I just can't stand not to.  In the course of doing this, I've
been trying to get myself Internet-connected under Linux, meaning that I've been
trying to get my external USR V.90 modem to work under Linux (it works OK under
Windows).

I installed Mandrake 6.0 recently, over an RH6.0 installation.  When I started
trying to get PPP going, I immediately found that nothing was getting through to
the modem, and I then found that even minicom wasn't able to talk to it (this is
after having gone into linuxconf and making the link for /dev/modem to
/dev/ttyS1 - DOS COM2:).  I got a clue to what might have been happening when I
used the setserial command on both ttyS0 and ttS1:  whereas the UART parameter
for ttyS0 showed up as 16550A, the one for ttyS1 showed up as simply "unknown."
Using setserial to force the parameter to 16550A did not help, and when I had
setserial autodetect, the parameter was set back to "unknown."  I/O adr and IRQ
values were set as I expected.

I don't know as a fact whether this thing's mobo has two identical UARTs or not,
but knowing that some PCs have differently-abled primary and secondary IDE
channels, it seems as though it's possible that it might have a 16550A for COM1
and something else for COM2.  The computer's docs yielded no useful info.  So,
before I go case-popping to determine just what runs COM2 or try to go through
the hassle of swapping the modem and the UPS on the two serial ports (knowing
that if I can't ever get COM2 to work, I'd have to forget having the UPS
interact with the system under Linux), has anyone come across a similar
situation?  Are there any UARTs that Linux just barfs on?  Does a determined
UART type of "unknown" for a serial port imply that it's unusable?

- Jeff