Date: Tue, 4 Apr 2006 20:20:43 -0700 (PDT) From: Doug Ambrisko <ambrisko@ambrisko.com> To: =?ISO-8859-1?Q?Jonas_B=FClow?= <jonas.bulow@servicefactory.se> Cc: freebsd-stable@freebsd.org Subject: Re: Issues with nullconsole in FreeBSD 6.0-p6 Message-ID: <200604050320.k353KhQP068029@ambrisko.com> In-Reply-To: <4431A0A3.50604@servicefactory.se>
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Jonas Bülow writes: | I'm experiencing a really strange problem using nullconsole in FreeBSD | 6.0-p6. Briefly, what happens is that the use of nullconsole affects | the behavior of the OS negatively, very negatively. | | There are two different setups with different kernel | configurations. They both have console set to nullconsole in | loader.conf. | | In the first setup the machine reboots spontaneously somewhere during | boot without leaving a hint of the reason. | | In the other setup there is a fsck process (fsck_4.2bsd) crashing with | signal 8 (floating point exception) during boot. The fsck is run on an | auxiliary disk during startup. | | Both these problems goes away if console is set to either vidconsole | or comconsole in loader.conf. | | Adding DDB to the kernel configuration prevents to machine from | continuously rebooting in the first setup. Instead, it silently halts | somewhere in the boot process. Not easy telling where. It's seems to | be somewhere late in the process. Probably when running rc.d scripts | by observing the time before reboot compared to when using vidconsole | or comconsole. | | I've tried to debug the problem. I've not figured out how to remotely | debug a kernel when using nullconsole. The escape to debugger hot keys | (Ctrl+Alt+Esc or Ctrl+SysReq) does not work when using | nullconsole. Therefor it is not possible to switch to remote mode. Can | DDB be force to go directly into remote mode? | | I really understand it is impossible to give a simple answer or | solution to my problems described above. Well, if someone knows a | solution I wouldn't mind sharing it. What I really would like help | with is some input on how to debug this further. What to look for, | things to try etc. We don't seem to have that problem here with our enhanced consmute stuff. I noticed some implementation strangeness with the newer consmute implementation. Our major change is to put it into a function so if you break into the debugger or it panics you get that stuff. Now technically this wouldn't be a good idea with the original motivation but works for us. Bug me to remember to extract the patch for you to try. Doug A.
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