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 delay as most unacceptable. Alexander Monakov's very simple patch always works for me but I haven't seen data from other people. Surajee has mentioned problems with it for some part of AMD's product range and, as one of AMD's IOMMU experts down at Austen Texas, he should know his onions :-). I would be tempted to run with the patch (11 x 20 msecs), log the exit count number and get some user feedback. Hopefully an improved patch will emerge! AMD may have commercial as well as technical reasons not leave it unaddressed. Best regards -- 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/1917203 Title: AMD-Vi: Unable to read/write to IOMMU perf counter Status in linux package in Ubuntu: In Progress Bug description: This boot warning (concealed by grub not taking over the fbcon console on a solo installation but always present on a multi-boot) has been bothering Linux users of AMD Ryzen machines for some time. The problem is currently under discussion at kernel level <https://bugzilla.kernel.org/show_bug.cgi?id=201753>. One solution proposed by Suravee Suthikulpanit <suravee.suthikulpa...@amd.com> <https://lkml.org/lkml/2021/2/8/486> works but inserts a boot-up delay of (at least) 100 msec. A second option by Alexander Monakov <amona...@ispras.ru> <https://bugzilla.kernel.org/show_bug.cgi?id=201753> also works but inserts no delay and more-or-less just moves one line of code. I've tried both solutions with kernel rebuilds for both Breezy kernel 5.8.18 and Hirsute kernel 5.10.11 and both work on my AMD Ryzen 2400G. Could I encourage your kernel experts to evaluate the situation (I think SuSE folk already are). My suggestion (as a humble user :-) ) would be to fold Alex's simple patch into your own list of kernel tweeks and get the correction out with the upcoming Hirsute release. Best regards and all respect! To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1917203/+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
