On 15.09.2021 04:40, Elliott Mitchell wrote: > On Tue, Sep 07, 2021 at 05:57:10PM +0200, Jan Beulich wrote: >> On 07.09.2021 17:03, Elliott Mitchell wrote: >>> Could be this system is in an >>> intergenerational hole, and some spot in the PVH/HVM code makes an >>> assumption of the presence of NPT guarantees presence of an operational >>> IOMMU. Otherwise if there was some copy and paste while writing IOMMU >>> code, some portion of the IOMMU code might be checking for presence of >>> NPT instead of presence of IOMMU. >> >> This is all very speculative; I consider what you suspect not very likely, >> but also not entirely impossible. This is not the least because for a >> long time we've been running without shared page tables on AMD. >> >> I'm afraid without technical data and without knowing how to repro, I >> don't see a way forward here. > > Downtimes are very expensive even for lower-end servers. Plus there is > the issue the system wasn't meant for development and thus never had > appropriate setup done. > > Experimentation with a system of similar age suggested another candidate. > System has a conventional BIOS. Might some dependancies on the presence > of UEFI snuck into the NPT code?
I can't think of any such, but as all of this is very nebulous I can't really rule out anything. Jan
