[PATCH 20/24] xen: update xen_add_to_physmap interface

On Wed, 1 Aug 2012, Konrad Rzeszutek Wilk wrote:

On Thu, Jul 26, 2012 at 04:34:02PM +0100, Stefano Stabellini wrote:

quoted

Update struct xen_add_to_physmap to be in sync with Xen's version of the
structure.
The size field was introduced by:

changeset:   24164:707d27fe03e7
user:        Jean Guyader [off-list ref]
date:        Fri Nov 18 13:42:08 2011 +0000
summary:     mm: New XENMEM space, XENMAPSPACE_gmfn_range

According to the comment:

"This new field .size is located in the 16 bits padding between .domid
and .space in struct xen_add_to_physmap to stay compatible with older
versions."

This is not true on ARM where there is not padding, but it is valid on
X86, so introducing size is safe on X86 and it is going to fix the
interace for ARM.

Has this been checked actually for backwards compatibility? It sounds
like it should work just fine with Xen 4.0 right?

I believe this also helps Mukesh's patches, so CC-ing him here for
his Ack.

I can put this in right now in tree if we are 100% sure its compatiblie with 4.0.

Yes, it is: 4 bytes integers are 4-byte aligned on 32 bit and 64 bit
on x86.