[Kernel-packages] [Bug 1917203] Re: AMD-Vi: Unable to read/write to IOMMU perf counter

Hi Alex! Herewith a summary of our accumulated results [1] for Surajee's IOMMU patch using 20 msecs wait and logged retries on AMD's Ryzen: Ryzen KernelColdWarm 4700U 5.11.0-116 1 3500U 5.11.7 5 6 2500U 5.8.0-455

[Kernel-packages] [Bug 1917203] Re: AMD-Vi: Unable to read/write to IOMMU perf counter

I've just tried Surajee's patch on Ubuntu's latest kernel 5.11.0-11 for upcoming Hirsute and it consistently unlatches IOMMU after 6 x 20 msec tries on my Ryzen 2400G. Mainline 5.12-rc2 gave identical results. Paul Menzel too gets failure even after 10 x 20 msecs on a 2200G and regards so long a

[Kernel-packages] [Bug 1917203] Re: AMD-Vi: Unable to read/write to IOMMU perf counter

Hi Alex! There are further results [1] for Suravee's patch on Ryzen 2500U (BubuXP) and 2400G (myself). Both show a slight difference between cold boot (retry 5 x 20 msecs = success) and warm boot (retry 6 x 20 msecs = failure). It would be worth (even slightly) increasing the number of retries

[Kernel-packages] [Bug 1917203] Re: AMD-Vi: Unable to read/write to IOMMU perf counter

Hi Alex! A splendidly prompt piece of cherry-picking. Many thanks. I've checked your test release on my Ryzen 2400G on current Ubuntu 20.10 and it still gives the diagostic: AMD-Vi: Unable to read/write to IOMMU perf counter It's to be expected! The little crew engaged with testing Suravee