Re: [patch] DTR/DSR hardware handshake support for 2.0/2.2/2.4

From: H. Peter Anvin (
Date: Wed Aug 02 2000 - 14:58:53 EST

Followup to: <>
By author: "Theodore Ts'o" <>
In newsgroup:
> Date: Tue, 01 Aug 2000 18:35:22 +0200
> From: Martin Schenk <>
> As I needed support for DTR/DSR hardware handshake to communicate with
> a serial printer (and the "wire RTS/CTS to DTR/DSR" tip from the
> serial-HOWTO works fine for a demo, but is not applicable for a few
> thousand POS terminals *gg*), I implemented this functionality.
> Yilch. This is specialized enough that I'd much rather this *not* go
> into the kernel. Next thing we know, someone will want a DTR/CD
> handshaking mechanism, etc.,etc.
> This should probably be a private kernel patch, or (much more strongly
> suggested) that you just get specially wired RS-232 cables. This is in
> fact a very standard thing to do, and you can order cables from Black
> Box or some other company specializing selling cables which connect
> crufty legacy hardware.

DTR/DSR is the most common handshake mechanism for RS-232-B (as
opposed to RS-232-C and RS-232-D) devices. This feature has been
requested on and off for the last five years. I think it's


<> at work, <> in private!
"Unix gives you enough rope to shoot yourself in the foot."

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