Linux on the Mac — state of the union [LWN.net]

Linux on the Mac — state of the union

Posted Dec 2, 2016 21:57 UTC (Fri) by bronson (subscriber, #4806)
Parent article: Linux on the Mac — state of the union

Phenomenal article. Very inspiring.

I'm surprised onboard display controllers don't support passthrough. It seems like that wouldn't take much silicon (except for the I/Os) and it would be a much simpler and cheaper architecture than the custom messes everyone is currently implementing.

I suppose there are two problems... 0. you might not want your powerful GPU to pass through the the cheapo chipset GPU, and 1. there's not enough demand to force nVidia and Intel to work together.

Back in the day, we thought dual-ported VRAM was snazzy. I say, dual-port the GPUs! Heck, daisy chain them.

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Linux on the Mac — state of the union

Posted Dec 3, 2016 21:37 UTC (Sat) by zlynx (guest, #2285) [Link] (3 responses)

It seems to me that Optimus / PRIME is already a pass-through solution. Instead of custom hardware it is sending the video buffer over PCIe to the GPU with the output on it. And it seems to me that we have this working pretty well these days.

Linux on the Mac — state of the union

Posted Dec 3, 2016 22:31 UTC (Sat) by bronson (subscriber, #4806) [Link] (2 responses)

Good point. If PCIe has the bandwidth and latency, then I'm happy to consider it a virtual passthrough.

It's hard to picture it being sufficient for a 4K or 5K monitor... but busses these days are pretty amazing.

Linux on the Mac — state of the union

Posted Dec 3, 2016 23:24 UTC (Sat) by excors (subscriber, #95769) [Link] (1 responses)

DisplayPort 1.3 apparently does around 26 Gbit/s, which is enough for 5K 60Hz. Modern NVIDIA GPUs support PCIe 3.0 x16, which is about 126 Gbit/s. That sounds like it should be plenty.

Linux on the Mac — state of the union

Posted Dec 4, 2016 18:29 UTC (Sun) by bronson (subscriber, #4806) [Link]

I agree, it seems possible, especially since the hardware was made for gamers. But I don't think that PCIe supports bandwidth reservations does it? Display traffic is scary finicky, and more throughput doesn't cure latency problems.

If it can do seamless 60Hz 5K PCIe-passthrough while the CPU is pegged and some bursty disk/network I/O is going on, then I'll buy it. Especially with an external monitor or two plugged in.