- Nov 11, 2018
- Asus ProArt Z690-Creator
- RX 6800 XT
- Classic Mac
- Mobile Phone
When we enable VT-d fully such that AppleVTD appears in IOReg, then on Big Sur and Monterey we are limited to 16GB memory. If we use more than 16GB memory, Ethernet and WiFi stop working. However, on Catalina and Mojave this does not happen, and hence any amount of memory is okay.Fair enough. I don't plan to make any changes on my own system but rather trying to be helpful to those that have Antelope interfaces but have been unable to use them. The default instructions on page one suggest that VT-d should be "Disabled" in BIOS. Though I understand why, I don't necessarily agree because there's a good reason why people bought Designare in the first place. That is to have a fully functioning (or as close to a real mac as possible) Thunderbolt. Unlike UAudio's Apollos which use onboard DSP to achieve low latency, most of Thunderbolt audio interfaces out there, require direct access to memory (DMA) typically reserved for virtualization (VT-d). I have helped a good half dozen people setting this up for a range of audio interfaces, from MOTU, Slate, Presonus and others.
I believe (I could be wrong) that in order to have a fully working Thunderbolt implementation, the following need to be true:
Recently I have been looking at building my own multi 10G switch for my homelab and some of the things this guy talks about, with respect to DMA and specific BIOS configurations, made a lot of sense and reminded me of the reasons why I had previously struggled to get my VRS8 going. It has to do with latency. Give this article a look as well and focus on the "Bounced Buffer" section.
- Enable VT-d in BIOS (assuming Thunderbolt devices are already enabled with 'no security' in BIOS)
- Remove dart=0 (Boot>Arguments in Clover / NVRAM>Add>boot-args in OC)
- Disabled SIP (if the installed driver doesn't produce a security prompt to allow driver to function)
It may be better for me to advise users of Mojave and Catalina of the benefits of VT-d and the procedure for enabling it. But Big Sur and Monterey users with more than 16GB will need to consider the tradeoffs.