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Date: Fri, 16 Jan 2026 13:42:36 +0200
From: Leon Romanovsky <leon@kernel.org>
To: Chuck Lever <cel@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>, Christoph Hellwig <hch@lst.de>,
	linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org,
	NeilBrown <neilb@ownmail.net>, Jeff Layton <jlayton@kernel.org>,
	Olga Kornievskaia <okorniev@redhat.com>,
	Dai Ngo <dai.ngo@oracle.com>, Tom Talpey <tom@talpey.com>,
	Chuck Lever <chuck.lever@oracle.com>
Subject: Re: [PATCH v1 3/4] RDMA/core: add MR support for bvec-based RDMA
 operations
Message-ID: <20260116114236.GG14359@unreal>
References: <20260114143948.3946615-1-cel@kernel.org>
 <20260114143948.3946615-4-cel@kernel.org>
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In-Reply-To: <20260114143948.3946615-4-cel@kernel.org>

On Wed, Jan 14, 2026 at 09:39:47AM -0500, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> The bvec-based RDMA API currently returns -EOPNOTSUPP when Memory
> Region registration is required. This prevents iWARP devices from
> using the bvec path, since iWARP requires MR registration for RDMA
> READ operations. The force_mr debug parameter is also unusable with
> bvec input.

I am not very familiar with iWARP. Do you know why we need a special
case here? Is there a reason we cannot avoid using scatterlists for
iWARP as well, now or in the future?

Thanks