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=?utf-8?B?Z2tNZDdJL0w0MEUvblBCdE1xNEtDcmNLMG9nZGxVVGdyMFhId1VoQT09?= X-Exchange-RoutingPolicyChecked: XH5yd2O0R63a3TeZ/J+efMNazAUMXt+GdcWODb0w8gZvJLGye8zuYFox2MWKspK4KubjGiZYaMpY7k24ZvpPpNynT6SJpdJN8crRb4C+edBB73r2g+TJVJh3Qd31VPqe2uDgqC1LDOBtKyh/yzb97hUrrBrHxkp5BJifU9hx4TuD1+0AlBlv0WhdhlmSAOwi261HUrvgeBkAXiyX/N7sJ21y96KwuLGBfN+vEhf3/RR4yymWu80Z4Gb/xNY0ItwqMkyMqjF8WurwxnaDgaoPOCgbZ2LD8vUZ/y8AkE8H9Q289De1p7SVpgCo/ExaEp6QG5sETZpLzKJjwo5yU30QTg== X-MS-Exchange-CrossTenant-Network-Message-Id: 3858e255-e0f0-4a1d-8fbc-08debb9e7314 X-MS-Exchange-CrossTenant-AuthSource: DM4PR11MB6020.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 May 2026 03:17:28.7374 (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: hUlw63BV/qGw3eDleKxik+6vOxFr3P0086u70Uh3QVLk7nfGlRg68mFPo5E3Dc0xXTMJYNoz5fTB1Itw+S9x/A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR11MB6852 X-OriginatorOrg: intel.com Hi Richard, On 5/26/2026 10:42 AM, Richard Cheng wrote: > L3_CAT measures cache isolation, which requires at least one ache bit > not shared with non-CPU agents, i.e. cbm_mask & ~shareable_bits != 0 . > On MPAM, shareable_bits == cbm_mask is a legitimate state, so there > might be situations that no bit can be reported as exclusive. > > Previously get_mask_no_shareable() does the check inside cat_run_test(), > which returns -1 silently and surfaced as a failure for arm64 MPAM. > > Implement cat_feature_check() to run the same check at feature-check > time, it prints a diagnostic and return false so the test case itself > can know when to skip. > > Signed-off-by: Richard Cheng We have also observed this issue, and the patch helps identify the root cause of the CAT test failure. ./resctrl_tests -t L3_CAT TAP version 13 # Pass: Check kernel supports resctrl filesystem # Pass: Check resctrl mountpoint "/sys/fs/resctrl" exists # resctrl filesystem not mounted # dmesg: [ 43.705792] resctrl: L3 allocation detected # dmesg: [ 43.712878] resctrl: L2 allocation detected # dmesg: [ 43.719856] resctrl: MB allocation detected # dmesg: [ 43.726800] resctrl: L3 monitoring detected 1..1 # Starting L3_CAT test ... # Mounting resctrl to "/sys/fs/resctrl" # All L3 bits are shareable; cannot measure CAT isolation ok 1 # SKIP Hardware does not support L3_CAT or L3_CAT is disabled # 1 skipped test(s) detected. Consider enabling relevant config options to improve coverage. # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0 Tested-by: Chen Yu thanks, Chenyu