Re: [dpdk-dev] [PATCH 2/4] vdpa/mlx5: support direct HW notifications

[Matan Azrad <matan@mellanox.com>]

From: Maxime Coquelin <maxime.coquelin@redhat.com>
> On 4/15/20 11:47 AM, Maxime Coquelin wrote:
> >
> >
> > On 3/24/20 3:24 PM, Asaf Penso wrote:
> >> From: Matan Azrad <matan@mellanox.com>
> >>
> >> Add support for the next 2 callbacks:
> >> get_vfio_device_fd and get_notify_area.
> >>
> >> This will allow direct HW doorbell ringing from guest and will save
> >> CPU usage in host.
> >>
> >> By this patch, the QEMU will map the physical address of the virtio
> >> device in guest directly to the physical address of the HW device
> >> doorbell.
> >>
> >> The guest doorbell write is 2 bytes transaction while some Mellanox
> >> nics support only 4 bytes transactions.
> >>
> >> Remove ConnectX-5 and BF1 devices support which don't support 2B
> >> doorbell writes for HW triggering.
> >
> > Couldn't we have different rte_vdpa_dev_ops depending on whether
> > doorbell write support?
> 
> I'll take the patch so that it lands into -rc1.
> But I would like to discuss the opportunity to have different dev_ops based
> on the device IDs, so that BF can still be supported. Maybe that could be
> done in -rc2?

Mellanox decided to remove BF1 from GA and from upstream support.
GA devices are CX6dx + BF2.

> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> Thanks,
> Maxime
>