Use Navi framebuffer in Sonoma without AVX 2.0 (RX6600 + Ivy Bridge)

[Krazubu]

Hi, 

A kind of incidental discovery.

I was testing Sonoma on my old Ivy bridge setup that I keep upgrading over the years, hoping it will make it one more time.

I had brought back an older RX580 because I knew that my RX6600 was supposedly a no go.

I install and setup all the stuff, used OCLP to add the Polaris kexts.

In the end I add my RX6600 back, just to ensure I won't have to physically swap the cards every time, and that its presence will not prevent Sonoma from working on the RX580. To my own surprise the RX6600 instantly worked without doing anything more !

 

What seems to be ok :

- Graphic acceleration

- Multiple displays, high resolution

 

What seems fishy :

- Though the system profiler tells metal is supported, my test in several apps show that the device doesn't seem to be detected as a metal one, the RX580 is available but not RX6600.

 

My wild guess is that the Polaris driver does some of the job in place of the not working AVX 2 Navi driver part

If so, a proper fix might not be far away.

This is still an early discovery, I will try to report progress here, if there is some.

 

Update : I'm back with some more info.

As I suspected, it was too good to be true, but I think the outcome is still interesting. I renamed the topic accordingly.

The Framebuffer for RX6600 does work, but not the metal driver. However, since there's an other card, all the GUI/metal acceleration is taken care of by the working RX580.

Though the benefit of this is limited, it's still interesting to know that you can let the Navi card and use its outputs, which can save the hassle of physically switching cards and display ports if you switch between several OSs. One configuration fits them all.

I pushed the idea to a less power hungry setting : HD4000 + RX6600.

The same result happens, all displays OK, and metal acceleration through the HD4000 (Though talking about "acceleration" is relative when dealing with HD4000 😜 )

 

To finish, a side question : why don't I see any reply option to this thread ?

 

[miliuco]

@Krazubu

Welcome back!

It's an interesting find, of course. You know that OCLP devs don't have fixed yet AMD 6000 series but maybe it's as you say and the RX 580 driver does something (incomplete) with the RX 6600.