Re: [PATCH 0 of 3] Update paging/sharing/access interfaces v2

[Olaf Hering <olaf@aepfle.de>]

On Fri, Feb 10, Andres Lagar-Cavilla wrote:

> Is there a timeout mechanism if out-of-tree consumers are not on the ball?

I would guess they need an adjustment for a step from 4.1 to 4.2.
Wasnt there already enough churn in the source in that area? And the
(old) SONAME is gone as well, so they need to be recompiled anyway.

> Actually, this hiatus allows me to float a perhaps cleaner way to map the
> ring: the known problem is that the pager may die abruptly, and Xen is
> still posting events to a page now belonging to some other dom0 process.
> This is dealt with in the qemu-dm case by stuffing the ring in an unused
> pfn (presumably somewhere in the mmio hole?)
> 
> Would that work? Is there a policy for parceling out these "magic pfn's"?

I was just thinking about this issue. The bug is that the ring lives in
dom0, the page should belong to domU and should be destroyed along with
it. And ring users in dom0 should request (and maybe initially allocate
and setup) a certain gfn belonging to domU.

Olaf