On Sat, Dec 22, 2018 at 01:37:58AM +0800, Yu Zhang wrote: > On Fri, Dec 21, 2018 at 12:04:49PM -0500, Michael S. Tsirkin wrote: > > On Sat, Dec 22, 2018 at 12:09:44AM +0800, Yu Zhang wrote: > > > Well, my understanding of the vt-d spec is that the address limitation in > > > DMAR are referring to the same concept of CPUID.MAXPHYSADDR. I do not > > > think > > > there's any different in the native scenario. :) > > > > I think native machines exist on which the two values are different. > > Is that true? > > I think the answer is not. My understanding is that HAW(host address wdith) is > the maximum physical address width a CPU can detects(by cpuid.0x80000008). > > I agree there are some addresses the CPU does not touch, but they are still in > the physical address space, and there's only one physical address space... > > B.R. > Yu
Ouch I thought we are talking about the virtual address size. I think I did have a box where VTD's virtual address size was smaller than CPU's. For physical one - we just need to make it as big as max supported memory right? -- MST
