eholley@cs.utexas.edu (Ed Holley) (11/25/88)
For anyone that is having trouble with the serial port driver: My serial driver absolutely refused to do anything at all. I eventually found that this was due to the transmit/receive buffer not being read after the modem was set up. By adding the following line to the bottom of procedure config_rs232 in rs232.c, I got my modem to work. port_in(base + RS232_TRANSMIT_HOLDING,&value); where value is declared as as integer. This clears out any interrupts the port thinks have occured, allowing more interrupts to occur. I hope this helps somebody else out there. Incidently, after spending all the time to figure this out, I discovered that this driver is not very usable, at least on my poor old slow PC compatable. But it does work. Ed Holley (eholley@cs.utexas.edu)
dtynan@sultra.UUCP (Der Tynan) (11/29/88)
Here are a couple of things I've been struggling with...
1/ The RS-232 channel is not flushed at any stage between an open()
and a close(). What this means, is my dialer program (which works
just fine under SysV) fails, because it finds junk still on the
line. The tty_open() routine should flush the buffer.
2/ There is no modem control, or support for SIGHUP, which makes
using the port as a dialin line difficult. Also, I would like
to share the line between dialin and dialout. As it stands, this
is impossible.
I don't know if these problems are from V7, or from Minix, but they are
troublesome. I am implementing a tty_open() and tty_close() scheme to
alleviate some of these difficulties. Film at eleven. For those people
who have asked that I post the diffs for eliminating the RAMDISK, please
be patient. I spent most of the holidays (in the US) trying to generate
the correct order for libc.a, as well as fixing some other problems. I
think I may have found a bug in malloc(). A program I am porting to
Minix would hang during an fopen() call. I traced it to a call to malloc().
I turned on the DEBUG option in malloc, and the problem went away. Any
comments? Another pet project when I get all this done, is to add shared
text to the PC version. I believe that MINIX-ST already has this (perhaps,
all I have to do is remove some #ifdef's?). I keep running out of space
from exec()'s. In the UN*X world, everyone does a popen() or system() as
a quick and dirty way to execute a child. Unfortunately, under Minix,
this results in yet another copy of the shell. Comments?
- Der
--
dtynan@zorba.Tynan.COM (Dermot Tynan @ Tynan Computers)
{apple,mips,pyramid,uunet}!Tynan.COM!dtynan
--- If the Law is for the People, then why do we need Lawyers? ---