Re: [virtio-comment] [PATCH 1/1] virtio-pmem: Support PCI BAR-relative addresses

[Cornelia Huck <cohuck@redhat.com>]

On Thu, Jul 22 2021, Taylor Stark <tstark@linux.microsoft.com> wrote:

> On Thu, Jul 22, 2021 at 01:24:17PM +0200, Cornelia Huck wrote:
>> On Wed, Jul 21 2021, tstark@linux.microsoft.com wrote:
>> 
>> > From: Taylor Stark <tstark@microsoft.com>
>> >
>> > Update the virtio-pmem RFC spec to add support for describing the pmem region
>> > via PCI BARs. Shared memory windows are used to accomplish this, similar to
>> > virtio-fs and virtio-gpu. This is required to support virtio-pmem in Hyper-V,
>> > since Hyper-V only allows PCI devices to operate on memory ranges defined via
>> > BARs.
>> 
>> Given that we already have pmem support out there (even though the spec
>> has not been included yet, should this get a feature?
>
> I wasn't sure if we needed to handle backwards compatibility given that pmem
> hasn't been merged into the spec yet. If we do, then yes I think it makes sense
> to add a feature bit. How about VIRTIO_PMEM_F_SHMEM_REGION?

Sounds good to me.

>> Also, requirements belong in a normative section; it's better to just
>> describe textually what the driver needs to do here and split out the
>> normative statements.
>
> Will do (ditto for your other comments). Thanks for the suggestions. It's
> a learning process for me - had to go and lookup what normative meant.. :)

If you have any further questions (or any suggestions how we can make
this easier for newcomers), feel free to follow up :)