Date: Thu, 07 Oct 2004 20:29:31 +0400 From: Roman Kurakin <rik@cronyx.ru> To: "Greg 'groggy' Lehey" <grog@FreeBSD.org> Cc: hackers@FreeBSD.org Subject: Re: Printing from kernel Message-ID: <41656EEB.5050602@cronyx.ru> In-Reply-To: <20041006230954.GO1350@wantadilla.lemis.com> References: <41645625.3020209@cronyx.ru> <20041006230954.GO1350@wantadilla.lemis.com>
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Greg 'groggy' Lehey wrote: >On Thursday, 7 October 2004 at 0:31:33 +0400, 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. >> >> >About the only thing I can think is that you're doing this in some >area where it's unsafe to print, probably holding a lock that's needed >in the print routines. > > I have the same idea but I cant't get which one. >> 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. >> >> Could anybody comment my observation? >> >> >Without more detail, it's impossible to help. > > >>Does anybody saw anything like this? >> >> > >No. printf() is widely used in the kernel. > > I know. But it seems that log is more safer ... >> 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. >> >> > >Take a look at your code and check what locks you're holding. Also, >if this is only for debugging, you should be using the kernel >debugger. > > It is used not only for debugging by myself, part of this output is my eye on users side. But for now, most of output is locking debugging. rik >Greg >-- >See complete headers for address and phone numbers. > >
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