Flex drivers and Win 11 conflict

David Edgar

I started my computer this morning and get a pop-up about device security and core isolation.

It took a bit but got it down to Flex drivers and something in Windows not working well together. The Flex version being 4.15.

I used Revo uninstaller, since it also scans the registry, to uninstall everything Flex.

I then reinstalled Flex 4.15 and now do not have a problem with device security nor core isolation.

I hope this doesn't revert to not being compatible.

I hope posting a thread about this may will help someone else with a similar issue.

VE7ATJ_Don

This has been a known 'bug'/issue for some time. The current set of DAX drivers will not install properly if Core Isolation is turned on within Windows Security. The workaround is to turn off Core Isolation. Doing so does not appear to affect overal security of the computer.

W7OWO

In some instances you may need to disable the Virtual Machine Platform (VMP) as well. This should only impact some hypervisors, and the Windows Linux environment as it runs as a virtual machine.
Settings -> Apps -> Optional features -> More Windows features
Action: Uncheck "Virtual Machine Platform"

Looking into the concerns for disabling of the security measure, it appears that it is the most critical during installation of software drivers. While it adds more administration to my PC, I do find many of the digital software I run can have frequent updates. So until the upgrade that has the fix in place is released, I will treat use Memory Integrity as a driver scanner, not a runtime feature. And turn in on prior to installing new software using a check-list similar as below:

DRIVER-SAFETY INSTALLATION PROCEDURE

Preparation Phase
1.1 Enable Virtual Machine Platform (VMP)
Path: Settings -> Apps -> Optional features -> More Windows features
Action: Check "Virtual Machine Platform"
Note: If Hyper-V was already enabled, leave it enabled. If not, leave it unchecked.
1.2 Enable Core Isolation / Memory Integrity
Path: Settings -> Privacy and Security -> Windows Security -> Device Security -> Core Isolation
Action: Turn "Memory Integrity" ON
1.3 Reboot the system
Purpose: Activates full virtualization-based driver enforcement

Installation and Testing Phase
2.1 Install the new software
Action: Run the installer normally
Note: If Windows blocks a driver, record the warning
2.2 Launch and test the software
Action: Use a non-critical radio or test environment
Verify:
- No DAX or virtual audio issues
- No virtual COM port failures
- No crashes or instability
- No abnormal CPU or latency behavior
Decision:
- If the software fails under these conditions, it contains non-compliant drivers
- If it behaves correctly, proceed to the next phase

Return to Radio-Friendly Configuration
3.1 Disable Virtual Machine Platform (VMP)
Path: Settings -> Apps -> Optional features -> More Windows features
Action: Uncheck "Virtual Machine Platform"
Note: Also uncheck Hyper-V unless you intentionally use it
3.2 Disable Core Isolation / Memory Integrity
Path: Settings -> Privacy and Security -> Windows Security -> Device Security -> Core Isolation
Action: Turn "Memory Integrity" OFF
3.3 Reboot the system
Purpose: Restores stable SmartSDR, DAX, and VSP/CAT operation

Normal Operation
4.1 Use SmartSDR and radio applications normally
4.2 Keep VMP and Memory Integrity disabled during regular radio operations
4.3 Repeat this procedure for any future software that installs drivers

Not enough experience yet, so it may require manually reinstalling the DAX drivers. There is a good link in the support section on FlexRadio.com

When looking into this issue, I created a helpdesk ticket. This was my first, and I appreciate the support that I got and some details of the issue. I was also informed they are testing updated DAX and VSP/CAT drivers for the next SmartSDR for Windows release.

I was also informed they will support ARM processors. That is good news to me for my use, I find I only need a good strong processing ability, without the expense of the GPU and cost of the graphic cards. ARM shines when the workload is CPU‑heavy but not GPU‑heavy. With ARM, because it has more security baked into the chip, drivers will need to be rewritten for it.

Brian - W7OWO