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PCI Express on the Raspberry Pi 4

mloduchowski.com

1–10 of 166 posts

Re: PCI Express on the Raspberry Pi 4

#4
post #2

That's really cool. I'm curious, would it be possible to use a modern GPU (running at 1x) on an ARM based board? Would the open source drivers that are part of the Kernel work out the box on ARM?

Yes, if you look around, people have even recompiled opensource drivers for RISC-V to use AMD cards.

Re: PCI Express on the Raspberry Pi 4

#5
It looks like an unreliable modification. Running a GHz-level interface with jumpers is almost impossible to control the impedance, it's a cool Proof-of-Concept though.

But is it possible to bring the project to the next level? Is it possible to make a daughterboard with QFN connector? If so, one can make a pin-compatible daughterboard with an extension connector. To use it, just desolder the USB chip and solder a new daughterboard on it, and you're ready to go. It would be one of the coolest Raspberry Pi projects!

Re: PCI Express on the Raspberry Pi 4

#6
post #2

That's really cool. I'm curious, would it be possible to use a modern GPU (running at 1x) on an ARM based board? Would the open source drivers that are part of the Kernel work out the box on ARM?

Hack’s creator here - it’s on my list of things to try. GPUs are notoriously hard to get to work on non-intel, having tried to get a few up on Alpha and Itaniums in the past.

VideoBIOS expects to run and expects a well behaving Intel CPU to do the power-up. That said X can sometimes emulate these quite well. On ARM we’d also run into alignment issues and likely other quirks - but in principle...

Re: PCI Express on the Raspberry Pi 4

#7
post #3

Hmm, how about using this for fast interconnect for making rpi clusters?

Wouldn't the gigabit LAN be a better fit for this? If you want to make a cluster, you need to make some custom hardware to connect to, that can facilitate the communication. At this point you're likely spending more that if you just bought a real desktop for more performance. I can see the fun factor in hacking the system together, though.

Re: PCI Express on the Raspberry Pi 4

#8
post #3

Hmm, how about using this for fast interconnect for making rpi clusters?

This might even allow some level of memory mapping in all directions. Unfortunately PCIe switches are not very hackable as such, but maybe I can spin a board for this purpose... after I get the hack more industrialized.

Re: PCI Express on the Raspberry Pi 4

#9
post #3

Hmm, how about using this for fast interconnect for making rpi clusters?

Wouldn't the gigabit LAN be a better fit for this? If you want to make a cluster, you need to make some custom hardware to connect to, that can facilitate the communication. At this point you're likely spending more that if you just bought a real desktop for more performance. I can see the fun factor in hacking the system together, though.

There are two ways of doing clusters - one is a message passing paradigm, which you can do over Ethernet (to an extent - I’d still take USB3 for 4x the bandwidth) - and the other is direct memory access a’la Cray.

What really motivated me to do this hack is the relative abundance of stuff I can now plug into an FPGA :)

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