I keep hoping PCIe host-to-host bridging (via Non-Transparent Bridging) will start to be popular/a thing. Alas right now I believe there's still only a single P

I keep hoping PCIe host-to-host bridging (via Non-Transparent Bridging) will start to be popular/a thing. Alas right now I believe there's still only a single PCIe controller on any given system that has NTB on it. You could concievably make a ring of systems, systems acting as a "client" device to their clockwise or anti-clockwise neighbor, but this is pretty low radix. You could make one system have a bunch of "client" hosts plugged into it, make a big hub spoke model, with radical oversubscription, but not sure what that would be good for. The article discusses something I'd love to spend years toying on: how to share & allocate the pools of resources on the upcoming fabrics: "If PCI-Express is going to be a fabric interconnect to lash together pools of CPUs, DPUs, GPUs, FPGAs, custom ASICs, storage, and memory, then someone is going to have to provide hypervisors to manage the virtualization layers here. We already have the means to manage virtual CPUs, GPUs, and storage, but no one as yet has created a memory hypervisor that will span local, near, and far memory banks across several racks — or maybe even a row — of machinery." Also worth nothing that AMD is only really shifting into gear to support NTB in a modern way, as they've just landed their PTDMA driver code, which is how they do NTB: https://www.phoronix.com/scan.php?page=news_item&px=AMD-PTDMA-For-Linux-5.15 https://www.phoronix.com/scan.php?page=news_item&px=AMD-PTDM... Would be lovely to see AMD show up here. My understanding is NTB doesn't require a lot of extra hardware. It'd be great to see AMD try to innovate & push. But right now AMD does not feel like they're doing much with interconenct technology. They have really good Infinity Fabric, but it's use is much smaller scale, powering their multi-chip packages, powering their inter-socket connections. They seem absent from USB4 & Thunderbolt support, don't seem to be pushing for integrated 25Gbit anywhere, unsure if they have any CCIX or CXL or GenZ stated intents. Doing something like supporting 4x NTB PCIe ports would be a massive massive upset, & capitalize on the huge PCIe AMD started leading with a couple years ago with the launch of EPYC.