To summary #1 Symptom: On AMD EPYC, ROME server platform, SATA hot plug not working on Ubuntu 22.04 LTS.
#2 Root cause: Ubuntu kernel compile with configure CONFIG_SATA_MOBILE_LPM_POLICY=3. During devices scan ( boot, pci scan, ahci driver load), if didn't detected any valid sata port or disk, it will power off the sata controller, so no event can get when plug in sata disk. It seems an expecting logic as AHCI spec shows that once LPM is enabled, then the hotplug needs to be disabled. # To enable hotplug by one of below 2 methods a. Add below kernel parameter can make sata hot plug working ahci.mobile_lpm_policy=1 In our test, set to 0 or 2 also works. Refer to #46 for what 0,1,2,3 represents. b. via proc file To set "max_performance" for "/sys/class/scsi_host/host*/link_power_management_policy" Set min_power or medium_power will enable power save and disable the "Hot Plug" again. # More info about mobile ALPM Aggressive Link Power Management (ALPM) is a mechanism where a SATA AHCI controller can put the SATA link that connects to the disk into a very low power mode during periods of zero I/O activity and into an active power state when work needs to be done. More refer to https://wiki.ubuntu.com/Kernel/PowerManagementALPM. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1971576 Title: SATA device hot plug regression on AMD EPYC (Asus) server Status in linux package in Ubuntu: Confirmed Bug description: SATA disk hot plug can't work on Ubuntu 20.04 ga-kernel of "Linux version 5.4.0-109-generic", but it works on earlier version of " Linux version 5.4.0-42-generic" To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1971576/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp