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

Bernard Metzler
2019-08-13T14:24:54Z

-----"Leon Romanovsky" <leon@kernel.org> wrote: -----

>To: "Doug Ledford" <dledford@redhat.com>
>From: "Leon Romanovsky" <leon@kernel.org>
>Date: 08/13/2019 12:30PM
>Cc: "Bernard Metzler" <bmt@zurich.ibm.com>,
>linux-rdma@vger.kernel.org, jgg@ziepe.ca
>Subject: [EXTERNAL] Re: [PATCH v2] Make user mmapped CQ arming flags
>field 32-bit size to remove 64-bit architecture dependency of siw.
>
>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 for the reminder, absolutely!

I created a PR#564.

Thanks very much,
Bernard.