I know TXT requires that TXT heap, AC and MLE must reside in DMA-protected region. DPR and PMR are two methods to handle it. The DPR (DMA protected range) is said to work at final check after VT-d in official development guide. It should be locked once initialized by BIOS. I guess it is a chipset function and can work without VT-d because it is controlled by TXT.DPR and I never found it in VT-d document.
So, if DPR is defined large enough to cover MLE (it said currently DPR is 3MB), can I say GETSEC[SENTER] can be executed without VT-d? Will AC check VT-d even if DPR is correctly set?
I want to know it beacuse my machine, Dell T3400 is equipped with X38 chipset. It is VT-d capable but I'm afraid BIOS do not enable it since I cannot find DMAR entry in ACPI. I prefer to do some experiments before I upgrade to a newer machine (it is unavoidable because the lastest AC module discontinues to support X38).