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Smith" , =?utf-8?q?Marek_Marczykowski-G=C3=B3recki?= , Dario Faggioli , Juergen Gross , George Dunlap , Subject: Re: [PATCH v4 10/12] xen: Rename CONFIG_HAS_DEVICE_TREE to CONFIG_HAS_DEVICE_TREE_DISCOVERY From: Alejandro Vallejo To: Jan Beulich X-Mailer: aerc 0.20.1 References: <20250620182859.23378-1-agarciav@amd.com> <20250620182859.23378-11-agarciav@amd.com> <490ee7bf-cb10-43e3-9416-9a68e7529b96@suse.com> <1fc40753-727e-408c-940e-07f3efe1ef48@suse.com> In-Reply-To: X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN3PEPF0000B06B:EE_|DS7PR12MB9526:EE_ X-MS-Office365-Filtering-Correlation-Id: 702f293c-8a20-47a9-7dd6-08ddb26814fd X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|7416014|36860700013|1800799024; X-Microsoft-Antispam-Message-Info: =?utf-8?B?djErbjdyTk5OSm1wUkpZeEtJa0xNeC85dEgvVEtld0RROW1rTUk2dFYwMjRs?= =?utf-8?B?cGhVNVgrMWxCRjVHaW5yUFkyWExacHh1elhObW50MzRvQWZDVVFTVlZKU0F3?= =?utf-8?B?ejhKN1pVWmxjU3NYazBPT0pLUkx2N2JZZXFXMWJ2bERBZHZ1RVd5UCthcHVm?= =?utf-8?B?L3p5WFQzNHNUMWxSZXRJcDYxT25uc1Yzc2Y4ajZiK0dIaTZucitCZUkxNEtJ?= =?utf-8?B?eDBNTUxremFpYi8vSlVXR2hzN0RaV2RwR01aUHZmNHZZOXlOSXVLWmh3QVQy?= =?utf-8?B?NFlrZFV5bzd2ek1pTzJTWWt1UlE2RkM4T0RkdzVud2RCY1o4ZlYyaDR0Mldj?= =?utf-8?B?RXlrV04xaWYzRkI3VE9HNWZZVmI3dzdvODlMb2RMWUxsNHFPNWFhMTVWWFFN?= =?utf-8?B?blM3Z2piSE85eExGVmZYYWhRdFlHcWMxWkRKZVdKSVNaeXFCVzVEY3JLT3pn?= =?utf-8?B?NHpNMUJtTHRGWEQ0bkhmZXpxMlJ6RlJ4NVZRZ0c4eHdDMEJoQ1hlcGF2WFYw?= =?utf-8?B?SW1QTnZHRnRjZ3l1TzhzalRmZzdzME1nVWZqSTBOQjhLdTMxd3FRUWNxejVR?= =?utf-8?B?ODQ5ZnljVStwdzZPZmp4Yng0SU9KMlJoR2ZiZkorN1BIbHltZGZVa3UyVUF2?= =?utf-8?B?NFJWQytIRzdoUHo0TDdpek5JcEhrQVVZTE9aWW5vd0czK2ZJMGxEaWlyaXFw?= =?utf-8?B?VnZZVXZrWXJuaHhzR2dweHhmUnlneDRjL2lLYzkyYkZyMHdrRmxZUzNRMFha?= =?utf-8?B?eUQ5dWVJcmFtbjY5bjBmYTZUQUJpdUk4YnRKbGNJSDhhWjlRTTN0NTR1Qjhk?= =?utf-8?B?SXh4OXVtTk53a1U2ZUtldlhhQlI3ZlEzWThvQXZKaUVLRHRiTmxEdWJYUkM2?= =?utf-8?B?bnlLdUVSRW9tNGxzanUwcFlFSTUrcjAwYTU0ZEZzKzlERGZhcFd0cmpXZ3Rj?= =?utf-8?B?K0sxK21lRlFtN0NIcTdvdERWd3kyczdpL1lXMnhoSk4rRjdZSDR0SVdvdUNm?= =?utf-8?B?b2VqdGxlVHQ5UkZzbHlRcC8wQ3NWaVlkeHZYSWxOSk5XMnJKU0hLUFNXdjd5?= =?utf-8?B?czQ3dDB5TXhTSHZXU25NS3JLTC9qQlprVlEyQzJiTjNEdFJJYS9ZZUgzSGFv?= =?utf-8?B?amptdWJWT0JlZ2EzMTlXeU5yUm0xOTdWTkkxWm9KeEozQURhK0ZTOUg3MGE2?= =?utf-8?B?dnYwSytOczg0RGpsbjc4Y0J0Y3B6QkFPSlVLbGlQUzYwdnkrTTNXWUd5Y1VD?= =?utf-8?B?L2JMNEVKa25VQW8wbmFDY0dqVWxqMU1SdWxwRHUvaDdGRDFKTUtsSGRtVE0z?= =?utf-8?B?eTBDM1VWRHlyQU9JYThEV3hXSjRHbzJCTFljVTRRN3J3MUw0d0lWeko4cHlC?= =?utf-8?B?aU9LZmRoREhiNjNud0hZUDNqdndNTUFJOHo1Yk5NdFVnQkgrNVRhOVVuNVNh?= =?utf-8?B?NVhwWXV1U2lQRVVHVnRWWGVXMGZpRXZ1SnRnc2Q5RkU1SHYwdWFpR1lQdWV6?= =?utf-8?B?OTdFOEZZR2I1TGU3dlF5Z0szK1FsTy9wVzA3YzJma0FiUXpwY3JweDVnc09M?= =?utf-8?B?bGVkSGdXTTVWWDhiWFBycWNSaXl1NDdETU96Rzl6WTFHNU1yU3dkWXExV1hP?= =?utf-8?B?VWR6TEdPMC9pdHMxNWJrMVZFTmlwQlFLTkZZVmxUV3JhU2UySUVFNW0wRU0r?= =?utf-8?B?cVo0aVRlUUlmZlc2bEtCemI1czNqRjFBVVo4djFpOEI1WVJUVFdqekM3Rm1z?= =?utf-8?B?LzFONjRHN3FoM2ZwMHptSlY2L3RlN1doTUpROUZOY2pVYUF2TSsxcWg2WVl3?= =?utf-8?B?NXJidVZEWXo2UjR5b1RTQzlWdE10ZzExMVNpSFdaT3RZQlJWZ0hzNmZsZEk4?= =?utf-8?B?emZsUTVDWmZERzZ1WnR5L1dRMEFxNVBuSlpjVXFpUlVRTThyNlBMdWxFZVR0?= =?utf-8?B?amJJd1VRdVBhN0F3bFlreDY4UGc5Ly8rQktNSGwxRElBWTM3N1ZQb3pKTEx4?= =?utf-8?B?U0t1VStENTV1T2VXL0svd25sMUhQN3JlUTcrczAyQ2J1K3QyTE9SUlNGTUZt?= =?utf-8?Q?puMyN2?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(82310400026)(376014)(7416014)(36860700013)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Jun 2025 15:10:25.4545 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 702f293c-8a20-47a9-7dd6-08ddb26814fd X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN3PEPF0000B06B.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB9526 On Mon Jun 23, 2025 at 4:26 PM CEST, Jan Beulich wrote: > On 23.06.2025 16:19, Alejandro Vallejo wrote: >> On Mon Jun 23, 2025 at 3:44 PM CEST, Jan Beulich wrote: >>> On 23.06.2025 15:11, Alejandro Vallejo wrote: >>>> On Mon Jun 23, 2025 at 9:39 AM CEST, Jan Beulich wrote: >>>>> On 20.06.2025 20:28, Alejandro Vallejo wrote: >>>>>> Moving forward the idea is for there to be: >>>>>> 1. Basic DT support: used by dom0less/hyperlaunch. >>>>>> 2. Full DT support: used for device discovery and HW setup. >>>>>> >>>>>> Rename HAS_DEVICE_TREE to HAS_DEVICE_TREE_DISCOVERY to describe (2),= while >>>>>> DOM0LESS_BOOT is left to describe (1). >>>>> >>>>> Considering hyperlaunch this feels wrong to me. Did you consider spli= tting >>>>> HAS_DEVICE_TREE into HAS_DEVICE_TREE_PARSE and HAS_DEVICE_TREE_DISCOV= ERY, >>>>> as I suggested on the committers call? You weren't there, but Stefano= said >>>>> he was taking notes. >>>> >>>> Some might've been lost is transit, I admit. I don't remember hearing = about >>>> a HAS_DEVICE_TREE_PARSE, but it might've very well been me being spott= y when >>>> syncing with Stefano. >>>> >>>> Having a special HAS_DEVICE_TREE_PARSE doesn't seem very helpful, as e= very >>>> arch would have it set. >>> >>> Hmm, yes, we don't want or need that. But then what's option 1 about? T= hat >>> shouldn't be "described" by DOM0LESS_BOOT. >>=20 >> It's about x86 using device_tree/ for hyperlaunch. x86 is the single use= r that >> doesn't need (2) at all. In the x86 case the same selector that picks = =20 >>=20 >>> >>>> I'd definitely like for the "enable support to boot >>>> several predefined domains from DTB descriptions" to be a single optio= n for both >>>> dom0less and hyperlaunch. And be selectable rather than unconditionall= y selected >>>> And ideally move towards a future in which both dom0less and hyperlaun= ch are one >>>> and the same. >>>> >>>> I can do an early rename s/HAS_DOM0LESS/HAS_PREDEFINED_DOMAINS and s/ >>>> DOM0LESS_BOOT/BOOT_PREDEFINED_DOMAINS/ if that helps. I was waiting to= do so >>>> until x86 gains the ability to boot off a DTB to avoid having help mes= sages >>>> describing things not yet on the tree. >>> >>> I have to admit that it's not clear to me if that would help. As you sa= y, on >>> x86 that's not a thing just yet. What I think we need to aim for is to = not >>> leave the tree in a state that's more confusing than anything else. Eve= n if >>> later (which may be much later) things would get tidied again. >>=20 >> Ok, how about turning it on its head? Seems like we're in agreement with >> HAS_DEVICE_TREE_DISCOVERY for Full DT support. There could be a DEVICE_T= REE_PARSE >> (no HAS_) that's selected by HAS_DEVICE_TREE_DISCOVERY and DOM0LESS_BOOT= . This >> allows x86 to deselect it by not picking DOM0LESS_BOOT. >>=20 >> Note that x86 cannot select DOM0LESS_BOOT yet, but that's how it'd compi= le-in >> hyperlaunch. In the meantime, the tree depends on DEVICE_TREE_PARSE inst= ead and >> device_tree/ is gated by DEVICE_TREE_PARSE only. >>=20 >> Sounds better? > > Yes. Except that in the last sentence of the previous paragraph: What's "= the > tree"? By "the tree", I meant the hypervisor tree. I just mean that Kconfig would = use DEVICEC_TREE_PARSE for selection purposes and the code would ifdef based on DEVICE_TREE_PARSE rather than DOM0LESS_BOOT rather than using the latter as= a proxy. =20 > And in device_tree/ wouldn't we end up with unreachable code on x86 > this way (the parts that are needed only by HAS_DEVICE_TREE_DISCOVERY)? They'd be compiled-out, just as they are now gated on HAS_DEVICE_TREE_DISCO= VERY on this patch. device-tree/ as a whole would be gated by DEVICE_TREE_PARSE, an= d each individual file inside might optionally be gated by stronger options. Cheers, Alejandro