Re: [PATCH] arch/x86: Fix kdump on x86 with physically hotadded CPUs

From: Thomas Gleixner
Date: Fri Oct 07 2016 - 04:05:15 EST

On Fri, 7 Oct 2016, Jiri Olsa wrote:
> On Thu, Oct 06, 2016 at 11:25:43AM -0400, Prarit Bhargava wrote:
> > I thought about doing this but it seems like every time some driver uses
> > topology_logical_package_id() the driver would have to replicate the error
> > checking code.
> hm, unless we guarantee topology_logical_package_id always
> returns sane values I dont see another way

I did some deeper investigation. So with prarits patch there is only one
possibility left to end up with an empty package id:

SMP Kernel on UP Machine, which has neither ACPI nor MADT. But those
machines are not a problem because they don't use any drivers which would
make use of it. Aside of that for UP we just can set the node of the cpu to
0 and be done with it. I'll pick up Prarits patch and amend it.