On 01/09/2014 10:57 PM, Yasuaki Ishimatsu wrote: > (2014/01/10 6:44), Vivek Goyal wrote: >> On Thu, Jan 09, 2014 at 04:34:16PM -0500, KOSAKI Motohiro wrote: >>> On Thu, Jan 9, 2014 at 10:00 AM, Vivek Goyal <vgoyal at redhat.com> wrote: >>>> On Thu, Jan 09, 2014 at 12:00:29AM +0100, Rafael J. Wysocki wrote: >>>> >>>> [..] >>>>>> The system then panics and the kdump/kexec kernel boots. During this boot >>>>>> ACPi is initialized and the kernel (as can be seen above) >>>>> >>>>> Which is a bug. You're not supposed to initialize ACPI twice in a row. >>>> >>>> [CC lkml, kexec mailing list, dave young] >>>> >>>> It is a fresh instance of kernel booting and it is initializing its data >>>> structures fresh. It is *not* re-initializing ACPI in same kernel. >>>> >>>>>> This patchset resolves the problem by adding a kernel parameter, >>>>>> no_memory_hotplug, to disable ACPI memory hotplug. It can be added by >>>>>> default >>>>>> as a parameter to the kexec/kdump kernel so the kernel boots correctly. >>>>> >>>>> This problem is specific to kexec/kdump, so please don't add *generic* command >>>>> line parameters to address this. >>>>> >>>> >>>> There are other command line options to solve kdump problems. In general >>>> one might want to disable memory hogplug on the fly even if it is compiled >>>> in the kernel. So it can act as a good debugging aid. >>>> >>>> Secondly, it can be specified with memmap=exactmap and mem=X paramters to >>>> make sure no memory is hot added in the system. >>>> >>>> So I can see other usages of this parameter. To me it makes sense to have >>>> a separate command line option to disable memory hotplug feature on the >>>> fly. >>> >>> I'm ok this option. But note, even if this option is specified, SH, >>> Power and S390 still >>> be able to use memory hotplug because their firmware are totally >>> different from ACPI. >>> >>> Maybe, adding acpi prefix provides good clarification. >> > >> Makes sense. Something like "acpi_no_memhotplug" or "acpi_disable_memhotplug" >> or something else. > > I like Prarit's patch and the boot option name. If it is updated, > I'll test it. I'm going with "acpi_no_memhotplug" and I'm testing across several systems right now. Will send out a new patch shortly. P. > > Thanks, > Yasuaki Ishimatsu > >> >> Thanks >> Vivek >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in >> the body of a message to majordomo at vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > >
