CPU: AMD Ryzen 5 5625U
Kernel: Linux HP-Laptop 5.15.0-58-lowlatency #64~20.04.1-Ubuntu SMP PREEMPT Fri Jan 6 18:45:25 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
I can't go to a newer kernel until they properly support ZFS... every kernel higher than this one that I've tested has failed to boot (including 5.15.0-60) at the point of importing pools.
In dmesg --level=warn, I'm getting:
pci 0000:00:00.2: can't derive routing for PCI INT A
pci 0000:00:00.2: PCI INT A: not connected
pci 0000:00:01.0: Adding to iommu group 0
pci 0000:00:02.0: Adding to iommu group 1
pci 0000:00:02.2: Adding to iommu group 2
pci 0000:00:08.0: Adding to iommu group 3
pci 0000:00:08.1: Adding to iommu group 4
pci 0000:00:08.2: Adding to iommu group 5
pci 0000:00:14.0: Adding to iommu group 6
pci 0000:00:14.3: Adding to iommu group 6
pci 0000:00:18.0: Adding to iommu group 7
pci 0000:00:18.1: Adding to iommu group 7
pci 0000:00:18.2: Adding to iommu group 7
pci 0000:00:18.3: Adding to iommu group 7
pci 0000:00:18.4: Adding to iommu group 7
pci 0000:00:18.5: Adding to iommu group 7
pci 0000:00:18.6: Adding to iommu group 7
pci 0000:00:18.7: Adding to iommu group 7
pci 0000:01:00.0: Adding to iommu group 8
pci 0000:02:00.0: Adding to iommu group 9
pci 0000:02:00.1: Adding to iommu group 10
pci 0000:02:00.2: Adding to iommu group 11
pci 0000:02:00.3: Adding to iommu group 12
pci 0000:02:00.4: Adding to iommu group 13
pci 0000:02:00.5: Adding to iommu group 14
pci 0000:02:00.6: Adding to iommu group 15
pci 0000:03:00.0: Adding to iommu group 16
pci 0000:03:00.1: Adding to iommu group 17
pci 0000:00:00.2: AMD-Vi: Found IOMMU cap 0x40
Then following on from that:
platform eisa.0: EISA: Cannot allocate resource for mainboard
platform eisa.0: Cannot allocate resource for EISA slot 1
platform eisa.0: Cannot allocate resource for EISA slot 2
platform eisa.0: Cannot allocate resource for EISA slot 3
platform eisa.0: Cannot allocate resource for EISA slot 4
platform eisa.0: Cannot allocate resource for EISA slot 5
platform eisa.0: Cannot allocate resource for EISA slot 6
platform eisa.0: Cannot allocate resource for EISA slot 7
platform eisa.0: Cannot allocate resource for EISA slot 8
Apparently a retry loop is needed to wait for power gating to discontinue, with some CPUs requiring upwards of 200 msec and multiple loop retries.
There's two different patches (but only one or the other should be used). The first one just loops more often than the original code:
https://lore.kernel.org/linux-iommu/20200529200738.1923-1-amonakov@ispras.ru/
... whereas the second one is more elegant, relocating init_iommu_perf_ctr check after the iommu_flush_all_caches, where it's guaranteed to work (and from there, downstream code gives fewer warnings and errors):
https://bugzilla.kernel.org/show_bug.cgi?id=201753
I believe one of those patches has been incorporated into the Zorin codebase... the first patch above, which just loops more than the original code.
If the devs could issue a patch based upon the second patch above, it'd be much appreciated by all Ryzen CPU owners.