Date: Wed, 28 Jun 2006 23:57:58 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: User Freebsd <freebsd@hub.org> Cc: freebsd-stable@freebsd.org Subject: Re: How to enter DDB through a terminal server / remote console ... ? Message-ID: <20060628235640.A78211@fledge.watson.org> In-Reply-To: <20060628193421.B43909@ganymede.hub.org> References: <20060628175839.F43909@ganymede.hub.org> <20060628232727.N78211@fledge.watson.org> <20060628193421.B43909@ganymede.hub.org>
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On Wed, 28 Jun 2006, User Freebsd wrote: > On Wed, 28 Jun 2006, Robert Watson wrote: > >> On Wed, 28 Jun 2006, User Freebsd wrote: >> >>> 'k, now that I'm up to 3 6-STABLE servers that are deadlocking, I'm >>> spending time with the remote tech today to get a serial console put >>> online ... how do I drop into DDB remotely, where the serial console is >>> going through a Portmaster Terminal server? issuing CTL-ALT-ESC, I doubt, >>> will work, will it? >> >> If configured to use a serial console (console="comconsole" in >> loader.conf), you can enter the debugger with BREAK_TO_DEBUGGER in the >> kernel config by sending a serial break. With my portmasters, I telnet to >> a TCP port to connect to the serial console, so I send a telnet break, >> using ^]send break. > > Have you ever had a problem with this warning: "(useful for remote > diagnostics, but also dangerous if you generate a spurious BREAK on the > serial port!)" in the handbook? Yes. It's unusual, but once in a while I get a nervous serial port. If you experience this, type "Cont" to continue, and then recompile your kernel with ALT_BREAK_TO_DEBUGGER but without BREAK_TO_DEBUGGER. Here's the notes entry: # Solaris implements a new BREAK which is initiated by a character # sequence CR ~ ^b which is similar to a familiar pattern used on # Sun servers by the Remote Console. options ALT_BREAK_TO_DEBUGGER I've not had problem a problem on any recent hardware except for my soekris. Robert N M Watson Computer Laboratory University of Cambridge
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