-----Original Message-----
From: Saleem, Shiraz <redacted>
Sent: Monday, September 13, 2021 8:50 AM
To: Leon Romanovsky <leon@kernel.org>; Ertman, David M
[off-list ref]
Cc: davem@davemloft.net; kuba@kernel.org; yongxin.liu@windriver.com;
Nguyen, Anthony L [off-list ref];
netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Brandeburg, Jesse
[off-list ref]; intel-wired-lan@lists.osuosl.org; linux-
rdma@vger.kernel.org; jgg@ziepe.ca; Williams, Dan J
[off-list ref]; Singhai, Anjali [off-list ref];
Parikh, Neerav [off-list ref]; Samudrala, Sridhar
[off-list ref]
Subject: RE: [PATCH RESEND net] ice: Correctly deal with PFs that do not
support RDMA

quoted

Subject: Re: [PATCH RESEND net] ice: Correctly deal with PFs that do not
support RDMA

On Thu, Sep 09, 2021 at 08:12:23AM -0700, Dave Ertman wrote:

quoted

There are two cases where the current PF does not support RDMA
functionality.  The first is if the NVM loaded on the device is set to
not support RDMA (common_caps.rdma is false).  The second is if the
kernel bonding driver has included the current PF in an active link
aggregate.

When the driver has determined that this PF does not support RDMA,
then auxiliary devices should not be created on the auxiliary bus.

This part is wrong, auxiliary devices should always be created, in your case it

will

quoted

be one eth device only without extra irdma device.

It is worth considering having an eth aux device/driver but is it a hard-and-
fast rule?
In this case, the RDMA-capable PCI network device spawns an auxiliary
device for RDMA
and the core driver is a network driver.

quoted

Your "bug" is that you mixed auxiliary bus devices with "regular" ones and

created

quoted

eth device not as auxiliary one. This is why you are calling to

auxiliary_device_init()

quoted

for RDMA only and fallback to non-auxiliary mode.

It's a design choice on how you carve out function(s) off your PCI core device
to be
managed by auxiliary driver(s) and not a bug.

Shiraz

Also, regardless of whether netdev functionality is carved out into an auxiliary device or not, this code would still be necessary.

We don't want to carve out an auxiliary device to support a functionality that the base PCI device does not support.  Not having
the RDMA auxiliary device for an auxiliary driver to bind to is how we differentiate between devices that support RDMA and those
that don't.

Thanks,
DaveE