Date: Thu, 07 Oct 2004 20:22:34 +0400 From: Roman Kurakin <rik@cronyx.ru> To: Don Lewis <truckman@FreeBSD.org> Cc: hackers@FreeBSD.org Subject: Re: Printing from kernel Message-ID: <41656D4A.3030406@cronyx.ru> In-Reply-To: <200410062324.i96NOc4b056930@gw.catspoiler.org> References: <200410062324.i96NOc4b056930@gw.catspoiler.org>
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Don Lewis wrote: >On 7 Oct, Roman Kurakin wrote: > > >>Hi, >> >> I have some problems with printing from kernel. >>At first I think that my problems was cause I use printf, >>but changed all of them to log cause it safe to use from >>interrupt handlers. The situation become better but I still >>observe system lockup in case I output some debug information >>from my driver. >> >> Also I have some problems with system console via com >>port. Instead of messages from kernel I see the first letter >>of the month name. >> >> > >This is a bug in syslogd related to non-blocking I/O that bde and I >discussed quite a while back, though we never figured out a proper fix. >I recently made the interesting discovery that the same problem isn't >present on sparc64. > >I think it'll start working again if you restart syslogd. > > From my observation I didn't came to conclusion that this could be due to syslog, but I'll check this. >> Could anybody comment my observation? Does anybody >>saw anything like this? >> >> Oh, I forget to say I observe that with both Current >>and Releng5, SMP. Also I can't trigger NMI so I can't see the >>point of lockup. >> >> > >I generally use printf for this sort of thing, and I was going to >suggest that you take a look at the KTR stuff, but that won't help if >the machine totally locks up so that you can't get to the KTR buffer. > >I think you'll have trouble getting close to the bug if you use log >because of the log latency from the generation of the message, passing >it through syslogd, and back to the kernel to be printed. > > I'll try to think up how to see where I have my problems. If you plan to work on this problems we could join our efforts, rik >_______________________________________________ >freebsd-hackers@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-hackers >To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" > > > >
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