Very Computer

So I've been messing with PPP on my 28K modem for a few days.
Apparently I have a problem with the serial port.  Just using Kermit to
talk to the modem at any higher than 9600 baud (say to print out
settings "at&v") drops characters.  Dialing and connecting at higher
than 9600 baud causes characters to be dropped left and right.

Linux thinks (in autoconfig) that I have a 16550A.  Besides, I can use
my machine in Windows 95 to connect at 57.6 with no problems at all.  I
guess this is the mysterious part. Why can't my serial port handle any
better than that on Linux?  Why would the serial connection work fine in
Win95 and not in Linux?

Is there a problem with my serial I/O? I have on board serial support
that supposedly is compatible with the 16550.  Is there a way to
increase my buffer size so characters don't get dropped?  Is there some
gotcha with the serial I/O and Linux that I'm missing?  Is there a
better serial driver?  Sigh....

Oh, I'm using the 2.0.15 kernel and I have been using hardware flow
control on the modem.

So I've been messing with PPP on my 28K modem for a few days.
Apparently I have a problem with the serial port.  Just using Kermit to
talk to the modem at any higher than 9600 baud (say to print out
settings "at&v") drops characters.  Dialing and connecting at higher
than 9600 baud causes characters to be dropped left and right.

Linux thinks (in autoconfig) that I have a 16550A.  Besides, I can use
my machine in Windows 95 to connect at 57.6 with no problems at all.  I
guess this is the mysterious part. Why can't my serial port handle any
better than that on Linux?  Why would the serial connection work fine in
Win95 and not in Linux?

Is there a problem with my serial I/O? I have on board serial support
that supposedly is compatible with the 16550.  Is there a way to
increase my buffer size so characters don't get dropped?  Is there some
gotcha with the serial I/O and Linux that I'm missing?  Is there a
better serial driver?  Sigh....

Oh, I'm using the 2.0.15 kernel and I have been using hardware flow
control on the modem.

Quote:Brian Chen writes:
>I have been using hardware flow control on the modem.

John.
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Have you cranked up the serial speed? Here's what I added to my rc.local:

            echo "Enabling RTS/CTS for modem."
            /bin/stty crtscts < /dev/cua1

            echo "Substitute 115kb when request 38.4kb."
            /bin/setserial /dev/cua1 spd_vhi

You might also want to set your asyncmap if you're running ppp. Check the
HOW-TO.

-Mike

Life is much simplier if you don't know what is going on.

 1) Enable CTS/RTS ("hardware") handshaking in your modem.
 2) Enable CTS/RTS ("hardware") handshaking in your PC (default in Linux)
 3) If you use IDE hard disks, then upgrade to linux-2.0.17
    and then use "hdparm -u1" on your drives from /etc/rc.d/rc.local

--

For Linux IDE (big/many) help, see:  /usr/src/linux/Documentation/ide.txt
For latest Linux kernels: ftp.cs.helsinki.fi:/pub/Software/Linux/Kernel/v2.0/