Re: [PATCH v2] Make user mmapped CQ arming flags field 32-bit size to remove 64-bit architecture dependency of siw.

From: Leon Romanovsky <leon@kernel.org>
To: Doug Ledford <dledford@redhat.com>
Cc: Bernard Metzler <bmt@zurich.ibm.com>,
	linux-rdma@vger.kernel.org, jgg@ziepe.ca
Subject: Re: [PATCH v2] Make user mmapped CQ arming flags field 32-bit size to remove 64-bit architecture dependency of siw.
Date: Tue, 13 Aug 2019 13:30:28 +0300	[thread overview]
Message-ID: <20190813103028.GH29138@mtr-leonro.mtl.com> (raw)
In-Reply-To: <a4e4215dab3715e0181fa6c97b583f3feb3d582d.camel@redhat.com>

On Mon, Aug 12, 2019 at 11:17:00AM -0400, Doug Ledford wrote:
> On Fri, 2019-08-09 at 17:18 +0200, Bernard Metzler wrote:
> > This patch changes the driver/user shared (mmapped) CQ notification
> > flags field from unsigned 64-bits size to unsigned 32-bits size. This
> > enables building siw on 32-bit architectures.
> >
> > This patch changes the siw-abi. On previously supported 64-bits
> > little-endian architectures, the old siw user library remains
> > usable, since the used 2 lowest bits of the new 32-bits field reside
> > at the same memory location as those of the old 64-bits field.
> > On 64-bits big-endian systems, the changes would break compatibility.
> > Given the very short time of availability of siw with the current ABI,
> > we do not expect current usage of siw on 64-bit big-endian systems.
> >
> > An according patch to change the siw user library fitting the new ABI
> > will be provided to rdma-core.
>
> I changed the commit message somewhat.  The siw driver was just taken
> into the upstream kernel this merge window, so there is no need to be
> apologetic about abi breakage, there are *no* released kernels with a
> prior abi.  We are only guaranteeing abi compatibility for the official
> siw as taken into the upstream kernel and into rdma-core, and those will
> be kept in sync starting with their first official release, which has
> not yet happened.  Until this rc cycle is complete, we can fix up
> anything that needs fixed up, so if there are any other abi issues you
> think you would like to address, well, chop! chop! ;-)
>
> With that said, thanks, applied to for-rc.
>

Please send relevant change to rdma-core too.

Thanks