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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?XuAF0iRLSvkWxJRiqkNbG337tFn7vAdL7kGO3xbuefnofgseqDrXmUYkzjgy?= =?us-ascii?Q?SxHFrxPOoWw3+QkiPOKpYeyss5aTjQ81krFCJl9CzdzrAoTHyGLs2h3p4j/u?= =?us-ascii?Q?c9x1so+yhO9IQmD5hEEY19sdzSMxnYW7yACQpdlysAQDNJ4a/Tw5XQtkO/Ac?= =?us-ascii?Q?0TNOBgSNJIAKe2y1YNWRlD6DYtW0fppldRGopBmCvCYkrCO1/CPmZ/hv+JhV?= =?us-ascii?Q?3p2IXn8lJ3GgtJkJ0eAFCV0wyEUxx4yrjRsCYOAc1TS0Wf8/1RIqB9+W01V2?= =?us-ascii?Q?mcxbNiCk3ie7RLOZ/p07PFdA3UuC4WJQcaejK3Hq6vMPZiwIpCKQLnaBbzoJ?= =?us-ascii?Q?7BZBJBpoj3Tq7w1W/+rX21twQZ2Dk+l04v7hOUqICIrc5aOjyBFlXKVqf7kC?= =?us-ascii?Q?MysmOj4Nr1ySXK0tGZtelnA0R+4LFe6teTPox8Ta8OUH9EkUl7bBj1CbZ3HV?= =?us-ascii?Q?ZprQC+nKNPI26QC178iChTn6RQk0OrOmj5I1/zp3u51NVt9sv156V8tb7Iai?= =?us-ascii?Q?gLWgdcHosnOnq3mxtmx3b2NrBE9iqzvUyQtocw8DPkADgRLROTjl3GqPQmcB?= =?us-ascii?Q?XZKK0ZsDkeAtMX/fB14uRKDW1xG5nURhVGzDuh/E6n4AUSpNnkrOh3gJiQlg?= =?us-ascii?Q?RNPxlVNQK8shzpgtBK3piBjevTvlLXUIRdoN43XmOeX7J4HXjKx0+urgroUa?= =?us-ascii?Q?B1xG8NsoSsj43xFvSE2B4kkJ8HvUUinBo8WgEMW0u+eWWgvl3thCjD0Yn72V?= =?us-ascii?Q?DH1Jc1d/LIrbIL7Cgy1cGo/Q0zEF4Es3DYS+h18PAKf8Z0HYwFj/lN5/JFPF?= =?us-ascii?Q?0AtWChazH5ilPDMfMSIxfJFMaFM4syez/bdMld50OiJt7XTgSHMAMyy3CWAn?= =?us-ascii?Q?egZ32MQbqb9vv0+g0IoUjv7MCODhvh2xSdaWpak0vCRp+sQTYDo0VXALR8ZZ?= =?us-ascii?Q?WpaZ64o5H93BlLw7RArmVumLnVK8MUzkzPz64UFJ50/y1xoKkeMmbExTWf+K?= =?us-ascii?Q?D8f/1VAay6C/FVh/FMI9OqK8yQES6M8eEoq4DW8YI+mLLh6DudPgD0GjxTY6?= =?us-ascii?Q?vWBFxvsOncifCnUSkjdjnFXEVXfUKopnTNddN92rx43V1P6o7KyO8ksm1yUi?= =?us-ascii?Q?m7AecctydToj+wbGqeSZoE8ADVu2ip4P5NvnuxXki0WiKB0i63+1hxgxQx49?= =?us-ascii?Q?qVx75jxKlAfljUBaeLwtW/SI0IPdlCNa2eApicEmZK8nrbFgevziavy6GnBm?= =?us-ascii?Q?tFqxCHqtl9CMPpfYRUQohbIdpFi2s7UKY8UvbExB0k5dVSjOsa48MH89EDG8?= =?us-ascii?Q?EBBkZcH0SMAcwMl9y0PYbjPAJm/gMyuwb3TLSa54l7qhDoi94BL4gfWSsG40?= =?us-ascii?Q?Sh+q0OG/ytLvUSXeApiDqVWSoX+ACfLo8xavuU8DEKypCANeaMSH4Q/2DnYq?= =?us-ascii?Q?XpXgUPXe8PpC44Di9QCr8jTD7JYaAbpjiBnwrD7Eaqc5X/t7yVLO65xmfPv4?= =?us-ascii?Q?O0gDyV8KjzGCNRhwzZL4syD2Pv7sewoCOUQTCaDDMiNK3ZEM30lkggexPPMw?= =?us-ascii?Q?RoIt3sFBgleh+B86ASWO+wZX4if9Gy/rR8+zAKm5?= X-MS-Exchange-CrossTenant-Network-Message-Id: 30b5f3f0-3ce7-48e7-4821-08da9c512b66 X-MS-Exchange-CrossTenant-AuthSource: SA1PR11MB6733.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Sep 2022 04:16:06.2785 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: bIvz8Wa3eluqOgRWqBcF9LabpMLqJEDr9gsIxDPl9PS6fFXHrL50wpex1i1SxX91pNsEsZnHPG4pzAW9lQ2OtQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR11MB5565 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org On Wed, Sep 21, 2022 at 05:36:42PM +0100, Jonathan Cameron wrote: > On Tue, 20 Sep 2022 15:10:26 -0700 > Ira Weiny wrote: > > > On Tue, Sep 20, 2022 at 01:23:29PM -0700, Jiang, Dave wrote: [snip] > > > > > > And what gets printed > > > to the trace buffer can be decoded data constructed from those fields by the > > > kernel code. So with that you can have access both. > > > > > > > Fast assigning the entire buffer + decoded versions will roughly double the > > trace event size. > > > > Thinking through this a bit more there is a sticking point. > > > > The difficulty will be ensuring that any new field names are documented such > > that when user space starts to look at them they can determine if that data > > appears as a new field or as part of a reserved field. > > > > For example if user space needs to access data in the reserved data now it can > > simply decode it. However, when that data becomes a field it no longer is part > > of the reserved data. So what user space would need to do is look for the > > field first (ie know the field name) and then if it does not appear extract it > > from the reserved data. > > > > I'm now wondering if I've wasted my time decoding anything since the kernel > > does not need to know anything about these fields. Because the above scenario > > means that user space may get ugly over time. > > > > That said I don't think it will present any incompatibilities. So perhaps we > > are ok? > > I favor decoding current record in kernel and packing it appropriately. > If that means we don't provide some new data from a future version then such > is life - the kernel needs upgrading. That information is unlikely to be > crucial - it's probably just more detail. Dave, Dan, and I discussed this further today. Dan expressed the same opinion. So I'm going to remove all the reserved fields from the next version. Thanks, Ira