I remember seeing this wasn't possible because the CPU uses 16KB page tables but GPUs only know how to work with 4KB but I can't find the reference anymore. I don't know if this just requires a change in VBIOS or a whole new GPU but it would mean it's up to nvidia, AMD, or Intel to make a Mac-specific GPU even though no Apple Silicon devices have PCIe slots so it would only be for the small minority of Mac users inside the small minority of eGPU users.
Under macOS? Not until Apple acts, I guess.
Presumably on linux this would "just work" (assuming drivers for the IO ports are written)?
Thunderbolt drivers are still WIP for Asahi so I’d assume eGPU support is still in the future.
I am skeptical that we will ever see that.
given that thunderbolt 3 is basically PCI,
the only far fetched part would be having to write a 3rd party driver for the card. Given the high end businesses that exist in this world to work with video on the (eg Davinci on the iPad which was recently on the front page), combined with a demand for absolute highest end GPU performance, I think there's a business case for it. I wouldn't hold my breath waiting for it to be open source though.
Considering how little commercial support there is for basic GPU functionality on regular Linux, it's wishful thinking to expect a mysterious stranger to write this code for you. Especially for black-box hardware.
I don't think this is generic eGPU support. AFAIK, Nvidia's render offloading is baked into their driver. Not sure if it has an AMD/Intel equivalent.
The mysterious strangers I have in mind are Blackmagic Design, who write Davinci Resolve, for both Mac and Linux, and have the economic incentive to. They made $576 million in revenue last year so it's not that far fetched.
AMD gpu drivers are open source and already work on multiple platforms thanks to being part of the kernel and Mesa.
The Linux kernel, yes. I was thinking of Darwin when I wrote that