Re: Latest tip kernel(3.2-rc1-tip_cf6b3899) fails to boot on x3850x5 machine

[Suresh Siddha <suresh.b.siddha@intel.com>]

On Thu, 2011-12-15 at 11:16 -0800, Yinghai Lu wrote:
> On Wed, Dec 14, 2011 at 11:19 PM, Ingo Molnar <mingo@elte.hu> wrote:
> >
> > * Yinghai Lu <yinghai@kernel.org> wrote:
> >
> >> On Wed, Dec 14, 2011 at 6:24 PM, Nikunj A Dadhania
> >> <nikunj@linux.vnet.ibm.com> wrote:
> >> >>
> >> >> BIOS pre-enabled x2apic, and kernel config does not have x2apic enabled?
> >> > make oldconfig somehow skipped this!! I can see my previous kernel config
> >> > having this enabled.
> >>
> >> looks like recent dmar table related DMAR changing cause that.
> >
> > Which one would that be? Perhaps:
> >
> >      iommu: Rename the DMAR and INTR_REMAP config options
> >
> > ? They then need to be fixed if it can be done sanely.
> 
> yes.

Not quite sure if I understand the reported issue.

If the old config file had CONFIG_X86_X2APIC and CONFIG_INTR_REMAP set,
doing "make oldconfig" on the newer kernel is asking if I want the new
CONFIG_IRQ_REMAP option to be set and if I say yes, then I have both
CONFIG_X86_X2APIC and CONFIG_IRQ_REMAP set and all is well.

But if I say no, then as expected CONFIG_X86_X2APIC gets disabled (as
IRQ_REMAP is not selected).

> @@ -287,7 +287,7 @@ config SMP
> 
>  config X86_X2APIC
>         bool "Support x2apic"
> -       depends on X86_LOCAL_APIC && X86_64 && INTR_REMAP
> +       depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
>         ---help---
>           This enables x2apic support on CPUs that have this feature.
> 
> 
> renaming INTR_REMAP IRQ_REMAP cause that.
> 
> Attached patch should fix the problem.
> 

While I am ok with the proposed patch (we are going back to the original
behavior which minimizes the number of options that the user need to
select), I am not sure if I understand the problem.

FWIW, Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>