On 17/11/15 10:26, Jan Beulich wrote: >>>> On 16.11.15 at 18:45, <andrew.coop...@citrix.com> wrote: >> Furthermore, it is unclear (given the unwritten ABI) whether it is even >> safe to move _PAGE_GNTTAB out of the way, as this is visible to a PV guest. > It seems pretty clear to me that this would be unsafe: It being > part of L1_DISALLOW_MASK, if it moved and a guest used the > bit for its own purposes, the guest would break. I guess we'll > need an ELF note by which the guest can advertise which of the > available bits it doesn't care about itself.
Well - it depends whether any of these bits actually get used. If none actually do get used, we would be better to retro-fit a real ABI in place, without requiring all new guests to opt-in to get new features. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
