From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Mon, 3 Aug 2015 23:54:17 +0200 From: Peter Zijlstra Subject: Re: [RFC] perf: Clear MSRs on kexec Message-ID: <20150803215417.GG25159@twins.programming.kicks-ass.net> References: <20150803213228.GC14481@krava.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20150803213228.GC14481@krava.redhat.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" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Jiri Olsa Cc: Don Zickus , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Ingo Molnar , Haren Myneni , dong.su@ericsson.com, Vivek Goyal On Mon, Aug 03, 2015 at 11:32:28PM +0200, Jiri Olsa wrote: > hi, > I'm getting following message on the kdump kernel start > > Broken BIOS detected, complain to your hardware vendor.\ > [Firmware Bug]: the BIOS has corrupted hw-PMU resources (MSR 38d is b0) > > it seems to be caused by NMI watchdog being configured > and fixed counter values stays in MSRs, which triggers > warning in check_hw_exists and disables perf support > in kdump kernel.. which probably does not hurt ;-) > > zeroing MSRs during kdump shutdown seems to work (attached) > but I'm not sure thats correct place for kdump perf callback Right, but why bother? All that kernel needs to do is write a memory dump to someplace and reboot, right? The less you do, the less can go wrong. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec