Re: [PROPOSED REMOVAL] PV guest superpage mappings

[Dave McCracken <dcm@mccr.org>]

On Wednesday, July 20, 2011, Keir Fraser wrote:
> The PV superpage mapping feature has been in the hypervisor for a while
> now, but I'm not away of any use of this feature by an upstream guest
> kernel (e.g., and primarily of interest, pv_ops Linux). Am I mistaken, or
> is anyone looking into or interested in this? If the feature is unused we
> should remove it from the hypervisor in this development cycle, as it's
> untested and is nothing more than a maintenance burden and security risk.
> If the feature is only used by vendor patches, the hypervisor-side
> implementation belongs in that vendor's patch queues too.

I submitted a patch to use this feature to Jeremy for inclusion in the Linux 
kernel tree back when it first went into the hypervisor.  I was under the 
impression it was in his tree, and would eventually make its way into mainline 
Linux.

I must admit I moved on to other projects and did not follow it carefully.  
What is the current path for Xen-specific patches to be included in Linux 
mainline?

This feature is important for hugepages to work well in a Xen guest.

Dave McCracken
Oracle Corp.
dave.mccracken@oracle.com