From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from wm58.inbox.com ([64.135.83.58]) by bombadil.infradead.org with smtp (Exim 4.69 #1 (Red Hat Linux)) id 1MFUpP-0005D0-3L for kexec@lists.infradead.org; Sat, 13 Jun 2009 15:07:37 +0000 Received: from inbox.com (127.0.0.1:25) by inbox.com with [InBox.Com SMTP Server] id <906130003489.WM58> for from ; Sat, 13 Jun 2009 7:08:58 AM -0800 Mime-Version: 1.0 Date: Sat, 13 Jun 2009 07:08:58 -0800 Message-ID: From: Dharmosoth Seetharam Subject: Re: /var/log/messages doesn't have crash info when kernel gets panic/oops/crash In-Reply-To: References: <9c8decfb07c.00000038dseetharam@inbox.com> <9e4e2f1ef78.00000173dseetharam@inbox.com> <9fe503a86b2.000002e5dseetharam@inbox.com> <913da90c6c8.0000039bdseetharam@inbox.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: "Eric W. Biederman" Cc: Neil Horman , vgoyal@in.ibm.com, kexec@lists.infradead.org, fastboot@lists.linux-foundation.org > -----Original Message----- > From: ebiederm@xmission.com > Sent: Sat, 13 Jun 2009 07:08:50 -0700 > To: dseetharam@inbox.com > Subject: Re: /var/log/messages doesn't have crash info when kernel gets > panic/oops/crash > > Dharmosoth Seetharam writes: > >>>>> Basic questions. >>>>> 1) Do you have panic on oops set? >>>>> I think that setting more than anything else will be the >>>>> difference in what shows up in /var/log/messages. >>>> >>>> Yes, in my case panic_on_oops was set with 1 >>> >>> That is the reason thing don't show up in /var/log/messages >>> because you panic before syslog has a chance to write the messages. >> >> Thanks. >> So, if panic_on_oops set with 0(default), we will get all the >> needed info like stack traces, bug info etc. in /var/log/messages then >> reboots. >> >> Or do we need to apply any specific patches to get info in >> /var/log/messages? >> >>> >>>>> 2) Have you tried a dry run and confirmed you can get a crash dump? >>>> >>>> No, I haven't tried this. >>> >>> It sounds like you have not been getting the coredumps when problems >>> happen. Running a simple test run to Alt-sysrq-c to confirm >>> that things are basically setup ok is a good idea. >>> >> Sorry, I misunderstood your question. >> I have gave dry run and confirmed that the dumps are getting saved in >> particular dir and able to analyze. >> >> I did in both the ways like >> 1 - echo c > /proc/sysrq-trigger >> 2 -Alt -sysrq -c > > Then unless you are having problems capturing core dumps in real > failure situations it sounds like all is well with the world. > > A kernel oops is normally not fatal and the kernel tries to limp along > allowing for better diagnostics etc. This allows klogd to read the > kernels message buffer and pass the kernel messages to syslog which > writes the messages to /var/log/messages. > > After a kernel panic nothing is allowed to happen which prevents > user space from writing to /var/log/messages in the usual way. > > If you want data in /var/log/messages it appears you have two choices. > 1) Post process a core dump as Neil suggested and feed the kernel log > buffer to syslog. > 2) disable panic on oops. The system will continue to limp along > allowing > user space to write to /var/log/messages. > > Eric Thanks Eric. I will try all the ways as you suggested and let you know the outcome. regards, Seetharam ____________________________________________________________ FREE ONLINE PHOTOSHARING - Share your photos online with your friends and family! Visit http://www.inbox.com/photosharing to find out more! _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec