On Mon, Jul 20, 2020 at 05:43:05AM -0700, Kenneth R. Crudup wrote: > > Thank you for getting back to me. > > On Mon, 20 Jul 2020, Mika Westerberg wrote: > > > It is done on purpose. The BIOS generates new UUID every boot. > > I see. This leads to a couple of follow-on questions, then: > > There are two "competing" Linux packages for controlling/admining TB, > "bolt" (which includes "boltctl") and "thunderbolt-tools" (which includes > "tbtadm". I used to have both installed but I think they sometimes get > in each other's way and settled on "thunderbolt-tools" as "bolt" was > leaving large numbers of UUID-related files over time. > > - Do you have a preference for either? bolt I suggest to report this to bolt upstream. > I've noticed that I can't seem to get IOMMU protection unless I boot > with Secure Boot on in my BIOS (which I never use, as I don't sign my > own kernels). IOMMU/DMAR is on in my kernel. > > - Is there any way to force this, or is this expected? I don't get the > "iommu_dma_protection" set on my controllers either. It depends on the system. The kernel expects that you have ACPI DMAR table with bit 2 set (platform opt-in). Some systems I have seen have "Native Security for Thunderbolt" or similar BIOS option that can be used to enable this and others have it enabled by default. > Finally, every now and then on a reboot, my TB dock "flaps" (repeatedly > connects and disconnects) and I have to either connect/reconnect the TB3 > cable, or initate a power-off. I suspect this is a BIOS bug (I also have > to set "intel_iommu=igfx_off" otherwise I get "DMA Hardware is malfunctioning" > errors on power-down (or hibernate)). > > - Have you seen this before or have any ideas? Not seen before, but IIRC some laptops require more power than what the dock can supply and the symptoms for that are similar that the connection goes down and then back up several times.
