Created attachment 206506 [details] Screen shot showing CPU type selections are now 32-bit only H/W: AMD Ryzen 7 3800X CPU, MSI MEG X570 ACE MB (no option to enable or disable virtualization) Relevant DMESG line: AMDFeatures2=0x75c237ff<LAHF,CMP,SVM,ExtAPIC,CR8,ABM,SSE4A,MAS,Prefetch,OSVW,IBS,SKINIT,WDT,TCE,Topology,PCXC,PNXC,DBE,PL2I,MWAITX, AMD Virtualization Reference: https://en.wikipedia.org/wiki/X86_virtualization#AMD_virtualization_(AMD-V) Relevant text: 'The CPU flag for AMD-V is "svm". This may be checked in BSD derivatives via dmesg or sysctl and in Linux via /proc/cpuinfo.' Previously created 64-bit VBox machines on earlier H/W and VBox are no longer "defined" as 64-bit machines. All machine type selections are now 32-bit only (see 'FBSD-VBox-5.2.18_no_64_bit.png' screen shot). Attempting to start a previously configured 64-bit VM now results in an error message (see 'FBSD-VBox-5.2.18_no_VTx_AMD-V_HW.png' screen shot) which further informs that CPU virtualization support is "missing".
Created attachment 206507 [details] VBox machine startup error message about no recognizable virtualization support
Could not find any relevant documentation at VirtualBox.org about CPU virtualization support or detection.
Created attachment 206523 [details] MSI MEG X570 ACE BIOS settings relevant to virtulization Two bits of information that I didn't have before: a) AMD virtualization (AMD-V) is also referred to as "SVM" b) MB virtualization settings are in Overclocking area which I skimmed over without making any changes upon initial system installation Needed to enable IOMMU and SVM Mode
Created attachment 206525 [details] Verification of MSI MB virtualization controls enabled Exiting from BIOS setup showing settings changes ("Global C-state" can be ignored)
Created attachment 206526 [details] OS boot messages verifying AMD SVM enabled FBSD boot messages showing expanded list of AMD CPU features now including expanded SVM list.
Created attachment 206528 [details] Additional verification of SVM ("Intel Secure Ring") More OS boot messages indicating active AMD SVM
So, I now have AMD-V (SVM) enabled and VirtualBox-5.2.18 recognizes 64-bit VM. So this PR can be closed.
VirtualBox Machine/Session Information now shows "VT-x/AMD-V" as Active.
One last clue that pointed me in the right direction came from, [Solved] No virtualization support with Gigabyte GA-AB350 Gaming 3? https://forum.level1techs.com/t/solved-no-virtualization-support-with-gigabyte-ga-ab350-gaming-3/114171
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