From mboxrd@z Thu Jan  1 00:00:00 1970
From: Grant Edwards <grante@visi.com>
To: ecos-discuss@sources.redhat.com
Subject: Re: [ECOS] Redboot: [xyz]modem via TCP?
Date: Wed, 18 Apr 2001 11:02:00 -0000
Message-id: <20010418130326.A20958@visi.com>
References: <20010206193724.58B8B7A814@visi.com> <20010208163254.A3275@visi.com>
X-SW-Source: 2001-04/msg00173.html

> > With Redboot, can you do [xyz]modem download via TCP instead of
> > serial port?
> 
> I slapped together a Python program that uses "sx" to download
> an S record file via TCP using xmodem protocol.  Small files
> (less than 2K or so) work fine, but when I get up to about 2K,
> RedBoot crashes.  I can load thelarge files fine via TFTP and
> xmodem/serial.

I've been messing around with this intermittently for a few
days and haven't made any progress.  I had to disable the
telnet command character processing in net_io.c so that x-modem
packets are allowed through "raw".  After that I can download
some files, but not others.  With DEBUG enabled in xyzModem.c,
I get errors because things (e.g. the ram_start variable) is
being overwritten by data from x-modem packets.  With DEBUG
disabled, I get different error behavior.  There must be a
buffer overflow somewhere, but I havn't been able to find it.

I've noticed that if the s-record code decides to give up, the
x-modem link isn't shut down gracefully and the other end keeps
sending retries that are interpreted by RedBoot as commands.
That's not very easy to fix since the s-record routines only
have a "getc()" routine to call and no way to shut down the
transfer when an error is detected.

Since x-modem won't work due to telnet command processing
anyway, I think I'm going to try a third "direct" mode where
the s-record file is accepted directly rather than being
encapsulated in x-modem packets.

-- 
Grant Edwards
grante@visi.com