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Date: Tue, 2 Apr 2024 15:45:54 -0300
From: Jason Gunthorpe <jgg@nvidia.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Leon Romanovsky <leon@kernel.org>, David Ahern <dsahern@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Christoph Hellwig <hch@infradead.org>,
	Saeed Mahameed <saeed@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Jiri Pirko <jiri@nvidia.com>, Leonid Bloch <lbloch@nvidia.com>,
	Itay Avraham <itayavr@nvidia.com>,
	Saeed Mahameed <saeedm@nvidia.com>,
	Aron Silverton <aron.silverton@oracle.com>,
	linux-kernel@vger.kernel.org,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Andy Gospodarek <andrew.gospodarek@broadcom.com>,
	Junxian Huang <huangjunxian6@hisilicon.com>
Subject: Re: [PATCH V4 0/5] mlx5 ConnectX control misc driver
Message-ID: <20240402184554.GQ946323@nvidia.com>
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On Mon, Apr 01, 2024 at 07:50:03AM -0700, Jakub Kicinski wrote:
> On Mon, 1 Apr 2024 15:30:03 +0300 Leon Romanovsky wrote:
> > > The proposal is an attempt at a common interface and common tooling to a
> > > degree but independent of any specific subsystem of which many are
> > > supported by the device.
> > > 
> > > Your responses continue to align with the notion that because the device
> > > can spit out ethernet frames, all diagnostics, debugging, configuration,
> > > etc. MUST go through networking APIs.
> > > 
> > > You seem unwilling to acknowledge that devices can work for various use
> > > cases without a netdev driver, and thus aspects of managing that device
> > > should be done outside of a netdev driver.  
> > 
> > HNS driver is a good example of such device. It has nothing to do with
> > netdev and needs common and reliable way to configure FW.
> 
> Sorry, I have a completely different reading of that thread.
> Thanks for bringing it up, tho.
> 
> As I said multiple times I agree that configuring custom parameters
> in RDMA is a necessity. Junxian's approach of putting such code in
> the RDMA driver / subsystem is more than reasonable. Even better,
> it looks like the API is fairly narrowly defined.

Uh, if I understand netdev rules aren't read/write sysfs created from
drivers banned? 

So reasonable for RDMA but unacceptable to netdev? My brain hurts.

FWIW, I've been trying to push RDMA away from driver created sysfs for
a while now. Aside from the API complexity, implementations have
messed up using the sysfs APIs and resulted in some significant
problems :(

Jason