Date: Sun, 10 Mar 2002 10:37:53 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Robert Watson <rwatson@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: Serial break into debugger broken from 'cu' on -CURRENT? Message-ID: <3C8BA801.2935DFB1@mindspring.com> References: <Pine.NEB.3.96L.1020310100210.61696P-100000@fledge.watson.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Robert Watson wrote: > For the past couple of months, I've been working with a set of identical > test boxes from SGI which, for some reason, stopped responding to serial > break on the serial console. I switched to the 'alternative break' option > in LINT, and things work fine. I assumed it was actually some issue with > that particular batch of machines, since no one else had had a problem, > and I didn't really have time to follow up. Yesterday, I brought online > two more crash boxes via serial console, both older TeleNet servers, and > noticed that neither of them respond to serial break over the serial > console using cu. This leads me to wonder two things: > > (1) Is serial break currently broken in -CURRENT > (2) Is serial break currently broken in 'cu'? > > I have't had a chance to follow up on either, but was wondering if anyone > else had experienced this? Essentially, hitting ~# in cu no longer > results in boxes dropping to the debugger. Enabling the alternative break > and using ~^B works fine, and Ctrl-Alt-Escape works fine on the real > console. The break signal is "At least 250ms of marking space" (line silence), according to the Bell 103C and 212A and B standards. There are two ways that UNIX programs try to do this; the first is an ioctl() for "send a break"; the second is to set the baud rate to 0, and then set it back after a sufficient time. You should check to see if both approaches (the working one and the non-working one) are trying to use the same approach, or not. If they aren't, it could be something as simple as the number of loops before the baud rate is set back is wrong for your clock speed, and the loops should be replaced with a call to nanosleep. 8-). -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3C8BA801.2935DFB1>