Date: Thu, 14 Jan 2016 23:25:26 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Bruce Evans <brde@optusnet.com.au> Cc: Warner Losh <imp@freebsd.org>, svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r294011 - head/share/man/man4 Message-ID: <20160114202526.GA37895@zxy.spb.ru> In-Reply-To: <20160115044315.T9902@besplex.bde.org> References: <201601141623.u0EGN7me063431@repo.freebsd.org> <20160115044315.T9902@besplex.bde.org>
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On Fri, Jan 15, 2016 at 06:27:05AM +1100, Bruce Evans wrote: > On Thu, 14 Jan 2016, Warner Losh wrote: > > > Log: > > Document how to enter the debugger here. I'm sure there's some better > > canonical place, and the nit-pickers are welcome to move this > > information there with a cross reference. > > ... > > Modified: head/share/man/man4/ddb.4 > > ============================================================================== > > --- head/share/man/man4/ddb.4 Thu Jan 14 16:21:58 2016 (r294010) > > +++ head/share/man/man4/ddb.4 Thu Jan 14 16:23:07 2016 (r294011) > > @@ -1435,6 +1435,47 @@ The NMI allows one to break into the deb > > ... > > +.Pp > > +For serial consoles, you can break to the debugger by sending a BREAK > > +condition on the serial line if > > +.Cd options BREAK_TO_DEBUGGER > > +is specified in the kernel. > > +Most terminal emulation programs can send a break sequence with a > > +special key sequence or via a menu item. > > +However, in some setups, sending the break can be difficult to arrange > > +or happens spuriously, so if the kernel contains > > This is all quite broken, though the above description is almost correct. > > The BREAK_TO_DEBUGGER option used to mean: enter (not break into) the > debugger using a serial line break. This is a good method, except it > is too easy to get serial line breaks. Unplugging the cable usually > gives on, and turning off the other end might give one. So this method > is only usable on local systems with secure cables that you don't trip > over or otherwise disconnect). > > This option was broken to mean: the default for the sysctl that controls > "breaking into" the debugger using either a serial line break or the console > key for "breaking into" the debugger. For almost perfection confusion, > this key is normally the "Ctrl-Print Screen" key on PC keyboards and > there is a "Break" key nearby. Ctrl-Alt-Esc also works. syscons(4) On may keyboard "Break" subscribe to "Pause", to "Print Screen" subscribe "SysReq".
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