Date: Wed, 15 Nov 1995 22:47:40 +1100 From: Bruce Evans <bde@zeta.org.au> To: current@freebsd.org, uhclem%nemesis@fw.ast.com Subject: Re: Serial HW flow control [was ISP state their FreeBSD concerns] Message-ID: <199511151147.WAA01311@godzilla.zeta.org.au>
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>I have personally not seen the precise problem with outgoing flow control >as the ISPs report, but I certainly have seen it with incoming, >particularly with modems with BIG buffers, such as the >Telebit WorldBlazer in UUCP Spoof mode under Turbo PEP. >The fix for me was in 1.1.5.1 (and still is in 2.1) to apply a patch to >uucico so that it enables hardware flow control - by default it does not, If you need hardware flow control of input, then you would have seen problems in 2.0 and 2.0.5 because hardware flow of input wasn't implemented in those releases. >nor does it seem to have a way to activate it from the config files as >was claimed when my suggested patch was pooh-poohed a year or so ago. See /etc/rc.serial. The modem() function gives reasonable settings for old modems. Change 57600 to 115200 for most current modems. >One of the ISPs is trying to let me borrow his communications monitor >so I can see exactly what they are talking about. They claim it will >show that they drop CTS and the processor has sent as many as 14 additional >characters after CTS was deasserted. If true, it sounds like our >hardware flow control does not "call-back" bytes already in the 16550 FIFO >like it should. As discussed in other mail you should see as many as 16 or 17 additional characters and an average of >= 8 while output is in progress (< 8 would mean that output is not streaming properly). Bruce
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