Syslinux - Dec 2003 - Question: anyone seeing excessive lost characters on SYSLINUX over serial port?

Hi all,

I have a user who is reporting excessive amounts of lost characters when 
using SYSLINUX (PXELINUX actually) over a serial port at 38400 bps. 
What is somewhat bizarre is that he has a very high quality server with 
a Cyclades board, and yet he's losing characters in the PXELINUX->server 
direction.  Has anyone else seen this?

Thanks,

	-hpa

Hello, Peter!

On Fri, Dec 05, 2003 at 07:18:18PM -0800, H. Peter Anvin
wrote:
> I have a user who is reporting excessive amounts of lost characters when 
> using SYSLINUX (PXELINUX actually) over a serial port at 38400 bps. 
> What is somewhat bizarre is that he has a very high quality server with 
> a Cyclades board, and yet he's losing characters in the
PXELINUX->server
> direction.  Has anyone else seen this?
I've seen such behaviour between two Linux boxes. I didn't have time to
investigate this, and used them at 19200. However, I suspect that this
behaviour was caused by disabled flow control (my cable lacked RTS/CTS,
so I didn't try enabling it).

Hope this helps,
Baurjan.

This could be flow control issue, this snippet comes from the 
cyclades.c driver source,
http://gate.csl.mtu.edu/lxr/http/source/drivers/char/cyclades.c , 

"The Cyclades driver implements HW flow control as any serial driver.
The cyclades_port structure member rflow and the vector rflow_thr 
allows us to take advantage of a special feature in the CD1400 to avoid 
data loss even when the system interrupt latency is too high. These flags 
are to be used only with very special applications. Setting these flags 
requires the use of a special cable (DTR and RTS reversed). In the new 
CD1400-based boards (rev. 6.00 or later), there is no need for special 
cables."

-----Original Message-----
From: Baurjan Ismagulov
To: syslinux at zytor.com
Sent: 12/8/2003 2:36 AM
Subject: Re: [syslinux] Question: anyone seeing excessive lost characters on
SYSLINUX over serial port?

Hello, Peter!

On Fri, Dec 05, 2003 at 07:18:18PM -0800, H. Peter Anvin
wrote:
> I have a user who is reporting excessive amounts of lost 
> characters when using SYSLINUX (PXELINUX actually) over a 
> serial port at 38400 bps.  What is somewhat bizarre is that 
> he has a very high quality server with a Cyclades board, and 
> yet he's losing characters in the PXELINUX->server direction.  
> Has anyone else seen this?