From: tytso@athena.mit.edu (Theodore Ts'o) Subject: Re: 0.99.4 killed my /dev/ttys0 Date: 30 Jan 1993 18:57:22 -0500
From: hymowitz@circle.cs.jhu.edu (Hymie!)
Date: 29 Jan 93 06:09:21 GMT
well, i just upgraded to 0.99.4, and ran into a small (well, big)
problem.
alas, when i ran ckermit 5a, i get an error that looked something like:
i/o error - unable to read character
0.99pl3 is much stricter about not allowing you to write to a port which
Linux doesn't think exists. Look in your bootup messages; the serial
driver is probably not configuring ttys0, either because (a) you have
AUTO_IRQ defined and you have a serial board which doesn't respond to
the AUTO_IRQ very well (I do have patches which should help fix this
problem, at least for some boards), or (b) you have an internal modem
with a Rockwell chipset, which does an imperfect emulation of a 16550A,
and thus doesn't pass the configuration tests. (If you have a Rockwell
chipset internal modem, and AUTO_IRQ works for your system, try
compiling a kernel which uses AUTO_IRQ).
If that doesn't work, grab the setserial program, which you can find on
tsx-11 in /pub/linux/sources/sbin/setserial.tar.Z, and compile it. This
will allow you to manually set the UART type to 16550A, with the
following command "setserial /dev/ttys0 uart 16550A", which should work
as a workaround.
- Ted