SLOW serial port in Linux !

SLOW serial port in Linux !

Post by Gerald Gutierr » Thu, 19 Oct 1995 04:00:00

If anyone could help me, it would be wonderful. A little while ago I
installed a Logitech 3 button bus mouse on my computer. The bus mouse
used IRQ5. Because my SB16 used to be on IRQ5, I changed the card
settings to IRQ10. I then added the append line to lilo.conf ( whch says
something to the order of sbpcd=230,SoundBlaster ), the irq
#define in bumouse.h, and recompiled the kernel without slip, ppp, nor
the sound card driver.

Most things seem to work just fine. I can access my Panasonic CDROM. gpm
and X can use the busmouse without problems. However .. the serial ports
( both COM1 and COM2, or /dev/ttyS0 and /dev/ttyS1 ) are totally hosed.
Whichever comm program I start, whether it be minicom or seyon, will
access the modem okay. When I type something to the modem, however, the
characters will come out one by one, with about a 15 second interval
inbetween each. Then -- no matter what command is sent, there is no reply
from the modem ( if I type AT<cr>, it doesn't spit out OK ). I've tried
all baud rates, both /dev/cua1 and /dev/ttyS1, etc... nothing seems to help.

There is another symptom. Because my system has 20megs, I compiled the
kernel to use more than 16megs of RAM. When I restarted with the new
kernel ( this is before I installed the busmouse and did any of the above
things ), the cdrom driver status lines ( which come up at bootup and
which go into /usr/adm/messages ) come up real slow .. one by one at
about 1 sec intervals. Interestingly enough, this slow'ness doesn't show
up when I compile for less than 16megs. This
'problem' continued after I installed the busmouse and did all the above.

Does anyone have any idea as to what is going on here ? I suspect
something wrong with the system's notion of what IRQ belongs to what
device. I'm not sure however. Any suggestions would be just wonderful.

Here are the interrupts, devices, and ioports files from the /proc
directory, in case there's anything useful.


 0:  199369 timer
 1:  5154 keyboard
 2:  0 + cascade
 5:  17887931 Busmouse
13:  1 math error
14:  11489 + ide0

Character devices:
 1 mem
 4 ttyp
 5 cua
 7 vcs
10 mouse

Block devices:
 2 fd
 3 ide0 25 sbpcd

0000-001f : dma1 0020-003f : pic1 0040-005f : timer 0060-0060 : kbd
0064-0064 : kbd 0070-007f : rtc 0080-009f : dma page reg 00a0-00bf : pic2
00c0-00df : dma2 00f0-00f1 : npu 00f8-00ff : npu 01f0-01f7 : ide0
0230-0233 : sbpcd 02f8-02ff : serial(auto) 03d4-03d5 : ega+ 03f6-03f6 :
ide0 03f8-03ff : serial(auto)

Thanks again.


1. linux serial port nullcabled to pc - slow start

Dear linux crowd,

would you please help me out with serial port connections?
I am very much a newbie in linux and I can't take time to learn this thing
on my own, but if you direct me to the right how-to that will help too.

I have null modem cable connection from linux to a pc. when linux is
first loaded this connection is established (thru kermit) very fast.
however if it is terminated improperly during the session the next
connection takes 1-2 minutes to establish.

First it says: removing the LCK...modem.. file
then it sits there for a minute of two and then it connects.

just removing this file before the connection doesn't help at all. The
only thing that i found to help is to reboot linux.

I am sure there should be some simple solution for that. Please help
me out


 __    __      ____   ____
|  \  |  \    /    | /    \  Egor Alekseev
|  \  |  \   /  /| |/ /|  \  SSEL, University of Michigan
|  \__|  \  /  /\|   /\|  \  URL:

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