Re: [PATCH] mm/page_alloc: Deprecate kernelcore=nn and movable_core=

[David Rientjes]

On Wed, 18 Jul 2018, Baoquan He wrote:

> > > We can still use 'kernelcore=mirror' or 'movable_node' for the usage
> > > of hotplug and movable zone. If somebody shows up with a valid usecase
> > > we can reconsider.
> > > 
> > 
> > We actively use kernelcore=n%, I had recently added support for the option 
> > in the first place in 4.17.  It's certainly not deprecated.
> 
> Thanks for telling. Just for curiosity, could you tell the scenario you
> are using kernelcore=n%? Since it evenly spread movable area on nodes,
> we may not be able to physically hot unplug/plug RAM.
> 

To evenly distribute ZONE_MOVABLE over a set of nodes regardless of the 
many memory capacities of systems that we have where individual command 
lines cannot be tuned.  But you want to deprecate kernelcore=nn, not just 
the percent version, so I assume that's not the answer you're looking for. 
We do not enable CONFIG_MEMORY_HOTPLUG so this deprecation would break our 
userspace such that we cannot use ZONE_MOVABLE.