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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: epam.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: PA4PR03MB7136.eurprd03.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 71c67647-1fbd-4dbd-3f70-08d9f1738dd1 X-MS-Exchange-CrossTenant-originalarrivaltime: 16 Feb 2022 17:41:25.1543 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b41b72d0-4e9f-4c26-8a69-f949f367c91d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: DwZRR42oTbdoXqi8IiNSu5OC/7h3KDXzIn8/H0iBZeBTWUUXB7ZdOd8KUqHaUHqbEgSfnaO70JjSMs0e+JtFSFunZXI0tzde9aSA1UEM/x4= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR03MB4185 X-Proofpoint-ORIG-GUID: E_SY76v2ChxxDTNXgVMnlBQXimE13RLy X-Proofpoint-GUID: E_SY76v2ChxxDTNXgVMnlBQXimE13RLy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-02-16_08,2022-02-16_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 lowpriorityscore=0 malwarescore=0 impostorscore=0 mlxlogscore=999 adultscore=0 mlxscore=0 bulkscore=0 spamscore=0 priorityscore=1501 phishscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2202160100 Hi Stefano, On Mon, Feb 14, 2022 at 02:05:18PM -0800, Stefano Stabellini wrote: > On Mon, 14 Feb 2022, Oleksii Moisieiev wrote: > > Hi Bertrand, > >=20 > > On Mon, Feb 14, 2022 at 11:27:21AM +0000, Bertrand Marquis wrote: > > > Hi Oleksii, > > >=20 > > > > On 14 Feb 2022, at 11:13, Oleksii Moisieiev wrote: > > > >=20 > > > > Hi Julien, > > > >=20 > > > > On Sat, Feb 12, 2022 at 12:43:56PM +0000, Julien Grall wrote: > > > >> Hi, > > > >>=20 > > > >> On 11/02/2022 11:18, Bertrand Marquis wrote: > > > >>> Do you plan to add support for other boards ? > > > >>>=20 > > > >>> Did you discuss more in general with the linux kernel guys to see= if this > > > >>> approach was agreed and will be adopted by other manufacturers ? > > > >>>=20 > > > >>> All in all I think this is a good idea but I fear that all this w= ill actually only > > > >>> be used by one board or one manufacturer and other might use a di= fferent > > > >>> strategy, I would like to unrisk this before merging this in Xen. > > > >>=20 > > > >> In the past we merged code that would only benefits one vendor (i.= e. EEMI). > > > >> That said, this was a vendor specific protocol. I believe the situ= ation is > > > >> different here because the spec is meant to be generic. > > > >>=20 > > > >>> @julien and Stefano: what is your view here ? > > > >>=20 > > > >> I share the same concerns as you. I think we need to make sure all= the > > > >> pieces we rely on (e.g. firmware, DT bindings) have been agreed be= fore we > > > >> can merge such code in Xen. > > > >>=20 > > > >> The first step is to have all the pieces available in public so th= ey can be > > > >> reviewed and tested together. > > > >> > > > >> Oleksii, on a separate e-mail, you said you made change for ATF. H= ow much of > > > >> those changes was related to support for Xen? If they are some, th= en I think > > > >> they should be upstreamed first. > > > >>=20 > > > >=20 > > > > Let me share changes, that were done to AT-F and Linux kernel > > > > device-tree in terms of the SCMI mediator POC. > > > > Changes to the Linux kernel: > > > > https://urldefense.com/v3/__https://github.com/oleksiimoisieiev/arm= -trusted-firmware/pull/4__;!!GF_29dbcQIUBPA!je9Cu0n0498Yn76OLWjxxVaB7jWJtyW= ycHX0YARezTnc7aYHpGRJ8tSxHqIC0fTMUUSV$ [github[.]com] > > > > Based on renesas-rcar linux-bsp, branch v5.10/rcar-5.0.0.rc5 > > > >=20 > > > > Changes to AT-F: > > > > https://urldefense.com/v3/__https://github.com/oleksiimoisieiev/lin= ux-bsp/pull/3__;!!GF_29dbcQIUBPA!je9Cu0n0498Yn76OLWjxxVaB7jWJtyWycHX0YARezT= nc7aYHpGRJ8tSxHqIC0eDKS3ge$ [github[.]com] > > > > Based on renesas-rcar/arm-trusted-firmware branch rcar_gen3_v2.5. > > >=20 > > > You inverted the links but thanks this is really useful. > > >=20 > >=20 > > That's strange. Links looks good from xen.markmail.org interface. > >=20 > > > Did you push the ATF changes to mainstream ATF or discuss those with > > > the maintainers ? > >=20 > > No. We did changes in ATF as a proof of concept. > >=20 > > >=20 > > > The strategy overall is nice but we need to make sure this is accepte= d and > > > merged by all parties (ATF and Linux) to make sure the support for t= his will > > > not only be available in Xen and for one board. >=20 > +1 >=20 >=20 > > I've prepared patch to Linux kernel, which is introducing scmi_devid > > binding, needed to set device permissions via SCMI. I've contacted > > Sudeep Holla , who is the maintainer of the SCMI = protocol > > drivers. Waiting for the response. > >=20 > > Changes to ATF are not Xen specific and were done in terms of POC. We d= o > > not have plans to upstream those changes right now. >=20 > If this work relies on a new interface in ATF, and the interface is not > vendor-specific, then at least the interface (if not the code) should be > reviewed and accepted by ATF. >=20 > Otherwise we risk ending up with an upstream SCMI implementation in Xen > that cannot be used anywhere, except the PoC. To make things worse, this > could happen: >=20 > - we upstream the SCMI mediator to Xen > - we upstream any required changes to Linux > - ATF rejects the SCMI-related interface changes > - ATF comes up with a difference interface >=20 > At this point we would have to deprecate the implementation in Xen. It > might also be difficult to do so due to versioning issues. We would > need to be able to detect which version of ATF we are running on, to > distinguish the ATF PoC version that works with the old interface from > the new ATF version that supports a different interface. >=20 > To avoid this kind of issues we typically expect that all relevant > communities agree on the public interfaces before upstreaming the code. That's sound reasonable. I'll contact with AT-F maintainers. Maybe I'll be able to upstream SCMI to AT-F. Also I hope I'll be able to contact Linux kernel SCMI maintainers and discuss device-tree structure. Best regards, Oleksii=