Re: [PATCH] acpi memory hotplug, add parameter to disable memoryhotplug for kexec

[Yasuaki Ishimatsu]

(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@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.

I like Prarit's patch and the boot option name. If it is updated,
I'll test it.

Thanks,
Yasuaki Ishimatsu

> 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


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/