Re: KVM "fake DAX" flushing interface - discussion
> I'd like to emphasize again, that I would prefer a
virtio-pmem only
> solution.
>
> There are architectures out there (e.g. s390x) that don't support
> NVDIMMs - there is no HW interface to expose any such stuff.
>
> However, with virtio-pmem, we could make it work also on architectures
> not having ACPI and friends.
ACPI and virtio-only can share the same pmem driver. There are two
parts to this, region discovery and setting up the pmem driver. For
discovery you can either have an NFIT-bus defined range, or a new
virtio-pmem-bus define it. As far as the pmem driver itself it's
agnostic to how the range is discovered.
And in addition to discovery + setup, we need the flush via virtio.
In other words, pmem consumes 'regions' from libnvdimm and
the a bus
provider like nfit, e820, or a new virtio-mechansim produce 'regions'.
That sounds good to me. I would like to see how the ACPI discovery
variant connects to a virtio ring.
The natural way for me would be:
A virtio-X device supplies a memory region ("discovery") and also the
interface for flushes for this device. So one virtio-X corresponds to
one pmem device. No ACPI to be involved (also not on architectures that
have ACPI)
--
Thanks,
David / dhildenb