Re: [virtio-dev] Re: [virtio-comment] [PATCH v3 2/3] content: Document balloon feature page poison

[Wei Wang <wei.w.wang@intel.com>]

On 05/26/2020 11:38 PM, Cornelia Huck wrote:
> On Tue, 26 May 2020 17:28:00 +0200
> David Hildenbrand <david@redhat.com> wrote:
>
> > On 26.05.20 16:50, Alexander Duyck wrote:
> > > On Tue, May 26, 2020 at 1:24 AM David Hildenbrand <david@redhat.com> wrote:
> > > > Still wondering what to do with free page hinting ... in the meantime
> > > > I'll have a look at free page reporting :)
> > > The problem is it is already out there so I worry we wouldn't ever be
> > > able to get rid of it. At most we could deprecate it, but we are still
> > > stuck with it consuming bit resources and such.
> > Yeah, that's not an issue, they will simply turn to dead bits with
> > minimal documentation. I just don't see us fixing/supporting that
> > feature, really. Let's see what @MST things when he has time to look
> > into this.
> If free page hinting is broken enough that we don't want anybody to try
> implementing it, we maybe could:

May I know the issues that you got with FREE_PAGE_HINT?

I thought the discussion was about the PAGE_POISON bit (not related to 
FREE_PAGE_HINT).
It just enables a way for guest to tell host about the poison value.
I think currently we don't have a usage in QEMU to use the poison value 
(not sure about other userspace),
so it's disabled by default.

Best,
Wei