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@xxxxxxxxxx> 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. Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
