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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?K/jtlAYoEP4Ja+s/59nSCMwmThjLORbKj9Ko04MZQHBwNvFQq+j943xnoYjf?= =?us-ascii?Q?TYqsmr8p0HtkoMh39LGOpWPxJjp9iqFu2ISizZHWyBrRnE/SsKs/lxnFbA9d?= =?us-ascii?Q?c3K6ohgnAr5IYXlKoX7KxvH4FHh0rA2/u3sRNLTAfJjywKzzC/ltuf8yavmK?= =?us-ascii?Q?p73jp1oFvoZcmVdKTffanOP5QqFlz5/4qpDU/w+kU8tSew+McW8XY82RLsNx?= =?us-ascii?Q?ezetD66N+6C2Tu/YsfP+MmkOmxCGzbGlQeO5KAbPpk2rJZDA04aLpR0ucNIF?= =?us-ascii?Q?QQD0JR6ekv1mked9XraJPoDgVPQ3CiWyvi5KQljazaCv5NYRiTOxkM938+i4?= =?us-ascii?Q?c/IWGlPNlRUVoI3VqSOI3USSoq3fgWpnRR0M378KsiCEtnSi7WcFCo0Y/uqL?= =?us-ascii?Q?E4qabXJ+WeqshA+uU16XM2titex/mf6kwQnx5KF82r5JmEukbz9sOno/wQnv?= =?us-ascii?Q?1yhvFDeff1AExaXkRPdif71FefwPXjWl3soyYPMchkF1v3ebRF33D+1udpug?= =?us-ascii?Q?MZtK/ph+5ZduSn7pOv9xlR9ncEUmiwV6VpzfVORSI74+ZvchgQnuNjzQ3O63?= =?us-ascii?Q?BZEH8DFOFZMifUT6ysErv7euUzi3Mg1xIMymRvodIPmO5wWXOI3yBIW/xF1u?= =?us-ascii?Q?n4F6QgrlQpnXROawSDCpO5+yB5zBToFLQFrUq/UF0+rkPpFoVgZxHhgMUnr5?= =?us-ascii?Q?N/ZAkQhYEs1FERVdwnfpQT5H/GzQCOrq4YoDT37nbpiZPBAyNNqjHzb3fSgt?= =?us-ascii?Q?MfV1aPJisnvh4qDSxW8EJahy24KFIy1zHmyhbIdS0PoMaORfl6rOjoovYNoc?= =?us-ascii?Q?K/oOnM3YTfwV9NPmFwiaeBvbfF2JvbOXBeqkQYoY1B5pEUlrNBcmLpZ+8QFj?= =?us-ascii?Q?QdZO9sY03nTr+yoXcnv8m60GQAAwb/gOAXZs6NwSl1LYXJh+HsS3LLnemkTu?= =?us-ascii?Q?WbgLgdRYBaosyWbjImiIkzuahHILC/HnhI693q2fap52e2ivCUYQmzvw7APP?= =?us-ascii?Q?/gNrs+j3YKLLYbWMDgbCfpvl7D/VjdUmlVpDQy6GTzHbzl5i65uOkQW1xUsd?= =?us-ascii?Q?NLje11xhdC15Z/jkMt8Uoksz4c0kQx32cWlVIr24wPHK3mic97159KY2zwU0?= =?us-ascii?Q?LKzwntBos5MKipS1WhHHGpEEPo25gzQPY+eyUWM1X5rxFnVv8lYnQVkNgm0I?= =?us-ascii?Q?HoVhiwlA9hwARW0Yj+Ez3ersY0B1eCPCL+UrtPhhzoS5mnB98rFf0EA8QfXd?= =?us-ascii?Q?WuNW4gwJWEbLm5hXCmkqHRxTPs7k978D7IKro2S4AJwrheZfLGCsDwBQQAiG?= =?us-ascii?Q?yEShJtoFdDIA6ml3766fQTgp9kDzrX1+j3WJWHEwQ5+eQfHyrO5WeIyuQzSS?= =?us-ascii?Q?uMy2KgnRzs33cKFKYlg/xwXYkgqDj+1Yj//lBxRoeDD25zvpSbxlpOSWHWwF?= =?us-ascii?Q?e1EfnunrmDAkQpO1mui2r9t4BgbY3zizhn5ic64g5W8odCy+ig/4z5n+2M3h?= =?us-ascii?Q?i4o3vH4krHCQy3JRiHQQ1EGQNGD6Ed3nBW7bVi17fhsvrY8kzHRoMuI0VOdB?= =?us-ascii?Q?mzRVEpUhxpBHJhE0edwHqcrgv4OrEGXSZFdl6WgI?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: e1377dd6-7eda-4b43-db53-08de13034009 X-MS-Exchange-CrossTenant-AuthSource: DM4PR12MB6373.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Oct 2025 13:43:01.7511 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: pnmpCqih/vMrV6yWDMbHW8BPZeN+cP4WmeLHPy8LCyErFbBmTKTabWA7Z5tlNG2q78gHv6Yu6o9POzruWwVZeA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB6799 On Fri, Oct 24, 2025 at 10:48:51AM +0200, Michal Pecio wrote: > On Thu, 23 Oct 2025 15:09:01 -0400, Yazen Ghannam wrote: [...] > > > Sorry for the rapid emails. Here's another interesting commit: > > f0551af02130 ("x86/topology: Ignore non-present APIC IDs in a present package") > > I have this commit on 6.12 but it doesn't help. > > As I understand, APIC ID is a bitfield of the form: > > [package ID] ... [core ID] [thread ID] > > In my case, per debugfs: > > domain: Thread shift: 0 dom_size: 1 max_threads: 1 > domain: Core shift: 2 dom_size: 4 max_threads: 4 > domain: Module shift: 2 dom_size: 1 max_threads: 4 > domain: Tile shift: 2 dom_size: 1 max_threads: 4 > domain: Die shift: 2 dom_size: 1 max_threads: 4 > domain: DieGrp shift: 2 dom_size: 1 max_threads: 4 > domain: Package shift: 2 dom_size: 1 max_threads: 4 > > So my phantom APICs simply look like another package with weird > non-sequential ID. (Probably not an ACPI spec violation yet?) > > f0551af02130 only rejects disabled APICs in the same packages as > enabled ones. An earlier proposal in that thread was to reject all > disabled APICs on bare metal unless explicitly "online capable": > > https://lore.kernel.org/all/87sf15ugsz.ffs@tglx/ > > This clearly goes against fed8d8773b8e and it seems to go against > what you wrote about AMD BIOSes potentially marking CPUs as disabled > in MADT and presumably allowing OS to wake them up with ACPI? Yes, that's right. It's not clear how this should be handled. :/ > > You asked elsewhere what happens if I online CPU5/6. I don't have > directories for them in /sys/, so not sure if I need any extra steps > to make them appear, or the kernel considers those CPUs bogus for > some reason and amd_nb could do the same? > > Bitmaps from /sys/: > /sys/devices/system/cpu/enabled:0-3 > /sys/devices/system/cpu/kernel_max:5 > /sys/devices/system/cpu/offline:4-5 > /sys/devices/system/cpu/online:0-3 > /sys/devices/system/cpu/possible:0-5 > /sys/devices/system/cpu/present:0-3 Right, good question. Why bother marking some CPUs as "possible" if we can't bring them online? > > I tried 6.18-rc2 and it's same thing, except EDAC and GART don't work. > On both kernels, possible_cpus=4 fixes it: > > [ 0.072066] CPU topo: Limiting to 4 possible CPUs > [ 0.072074] CPU topo: CPU limit of 4 reached. Ignoring further CPUs > [ 0.072082] IOAPIC[0]: apic_id 4, version 33, address 0xfec00000, GSI 0-23 > [ 0.072084] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl) > [ 0.072086] ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 low level) > [ 0.072089] ACPI: Using ACPI (MADT) for SMP configuration information > [ 0.072090] ACPI: HPET id: 0x8300 base: 0xfed00000 > [ 0.072097] CPU topo: Max. logical packages: 1 > [ 0.072097] CPU topo: Max. logical dies: 1 > [ 0.072098] CPU topo: Max. dies per package: 1 > [ 0.072103] CPU topo: Max. threads per core: 1 > [ 0.072105] CPU topo: Num. cores per package: 4 > [ 0.072105] CPU topo: Num. threads per package: 4 > [ 0.072106] CPU topo: Allowing 4 present CPUs plus 0 hotplug CPUs > [ 0.072107] CPU topo: Rejected CPUs 2 Thanks for checking this. By the way, have you looked through your BIOS settings to see if there's something relevant? Maybe there's an option to remove the bogus/placeholder APIC entries? Here's the K10 BKDG for reference: https://www.amd.com/content/dam/amd/en/documents/archived-tech-docs/programmer-references/31116.pdf The "CPU Cores and Downcoring" section has some explicit restrictions on what is possible. So maybe something there can be used to filter out bogus CPU entries. Thanks, Yazen