On Tue, Aug 04, 2015 at 07:52:29AM +0200, Jiri Olsa wrote: > On Mon, Aug 03, 2015 at 11:54:17PM +0200, Peter Zijlstra wrote: > > 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. > > well, I was hunting that 'Broken BIOS..' message which is wrong Not really. The previous kernel being the BIOS in this case did leave the counters in a funky state. > I wouldn't think anyone wants to use perf under kdump kernel, > but you never know ;-) Yeah, I think we knew about this back then (might've been 2010) and chose to not 'fix' it. http://lkml.iu.edu/hypermail/linux/kernel/1012.1/00380.html Is what google finds me.
