-----"Doug Ledford" <dledford@xxxxxxxxxx> wrote: -----
>To: "Bernard Metzler" <BMT@xxxxxxxxxxxxxx>, "Jason Gunthorpe"
><jgg@xxxxxxxx>
>From: "Doug Ledford" <dledford@xxxxxxxxxx>
>Date: 08/07/2019 08:53PM
>Cc: linux-rdma@xxxxxxxxxxxxxxx
>Subject: [EXTERNAL] Re: Re: [PATCH 1/1] Make user mmapped CQ arming
>flags field 32 bit size to remove 64 bit architecture dependency of
>siw.
>
>On Wed, 2019-08-07 at 17:49 +0000, Bernard Metzler wrote:
>>
>> It hurts, but I did finally setup qemu with a ppc image to check,
>> and so you are right!
>>
>> ...
>>
>> #ifdef __BIG_ENDIAN__
>>
>> seem to be available in both kernel and user land...
>>
>> But, general question: siw in its current shape isn't out
>> for long, older versions from github are already broken with
>> the abi. So, silently changing the abi at this stage of siw
>> deployment is no option? It's a hassle to see an old mistake
>> carried along forever with that #ifdef statement...no?
>
>I was thinking about that myself.
>
>This really hasn't been out long enough to completely tie our hands
>here. A point update to rdma-core will resolve any user side issues.
>
What we are aiming at is ensuring backward compatibility
for 64bit-BE architectures, which are using siw since this year.
The community is likely of size zero.
I found it hard to find a machine, even in the ppc world, which
let me test that BE thing. I ended up with an emulator. So I
assume it is no real world issue to now just change the 64bits
flag into 32bits and add a 32bit pad for ABI compliance.
At the other hand, the change would be marginal (but awkward!):
diff --git a/include/uapi/rdma/siw-abi.h b/include/uapi/rdma/siw-abi.h
index af735f55b291..162b861ad2ac 100644
--- a/include/uapi/rdma/siw-abi.h
+++ b/include/uapi/rdma/siw-abi.h
@@ -180,7 +180,12 @@ struct siw_cqe {
* to control CQ arming.
*/
struct siw_cq_ctrl {
+#ifdef __BIG_ENDIAN__
+ __u32 pad;
+ __u32 flags;
+#else
__u32 flags;
__u32 pad;
+#endif
};
#endif
I propose taking my initial patch (w/o conditional endianess code).
But I can live with the ugly. Let me know.
In any case, I will make a PR for the user lib, since we changed
the variable to 32 bits...
Thanks
Bernard.
>Are they doing stable kernel patches for the last kernel? If so, we
>can
>fix it both places. No distros have picked up the original ABI in
>this
>short of a window and managed to get it into a shipped product, so we
>can notify any that might have picked up the broken version and get
>that
>updated too if we don't dilly dally and make the call quickly.
>
>--
>Doug Ledford <dledford@xxxxxxxxxx>
> GPG KeyID: B826A3330E572FDD
> Fingerprint = AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD
>
[attachment "signature.asc" removed by Bernard Metzler/Zurich/IBM]
