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Date: Fri, 30 Jun 1995 12:06:11 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199506300206.MAA21212@godzilla.zeta.org.au>
To: CVS-commiters@freefall.cdrom.com, ache@freefall.cdrom.com,
        cvs-sys@freefall.cdrom.com
Subject: Re: cvs commit: src/sys/i386/isa sio.c
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>  Modified:    sys/i386/isa  sio.c
>  Log:
>  Fight with hanging modems continued:
>  return EIO after t_timeout expired instead infinite looping in "siotx"
>  in comparam, consuming CPU time.

Why does this loop occur?  It can't happen with working 8250..16550
chips?  It might happen if the UART incompatibly implements ctsflow
in hardware.  Otherwise, hangs here are quite different from the
ctsflow-related hangs solved elsewhere using t_timeout.

Bruce