risc-v and such

[jlambrecht]

Since i've got to know parallella i've been in doubt of buying one, with my skill level it's just an arm board with dead-weight fpga and epiphany. So, slowly, i started picking up a bit here and there on fpga and along the way i got to understand better what a killer bundle this parallella board actually is. By chance i also picked up on rex/neo and risc-v / lowrisc.

By now, i've grown bedazzled enough to have some questions.

[ risc-v] I've learned it also has soft processor cores and it's probably going to be the next core should any new adapteva/parallella product launch ( this year ? )
[ fpga ] can risc-v soft processors be uploaded to the existing Zync 7010 / 7020 fpga ? has it been tried, is it doable ?
[ epiphany ] this is a surplus question, is it evolving ? Will it become virtualized and become an FPGA-only board with the eMesh architecture as a NOC using the risc-v soft processor ? ( oh yeah, i'm both curious and speculative here )

I'm kind of convinced i can do something with a parallella board by now ( if not only for opencl based ids using the zync-fpga ? ) but it is still hard to find use for the epiphany from my point of view. Are there any uses for the parallella board if you're not a comp.science engineer or a hardware addict ?

[6thimage]

[DonQuichotte]

Totally agree with you, 6thimage ; a PCIe version would be a tremendous evolution
I even have a better dream if possible: a pilchard-like card. Pilchard was an FPGA you were inserting in a memory slot, that was space odyssey - I mean, in 2001.
You'd then get the better of both worlds: my 32 Gb DDR4 RAM would be as near as it could from my beloved Epiphany de la Parallella

I agree ; any code with (very low RAM needs and) lots of branchs should behave very well with Epiphany (penalty is only 0 or 3 cycles), much better than with GPU or heavy pipelined x86 CPU.
I've tried both ; GPU was a failure (same experiment from another guy) ; whereas Paralle2 - a simple backtracker for Eternity II-like puzzles - works great for Epiphany.
Epiphany does the same job as two thirds of a high end CPU single core (core i7 Haswell 5820k, turbo mode 3.6 GHz) - with low power 4.7 W instead of 72 W O_O
You should have few data and much computation ; I currently code a simple OCR (Optical Character Recognition), maybe it could fit too.

[sebraa]

I don't like the concept of PCIe cards anymore, since computers supporting them have been disappearing so much since the shift to mobile. A USB-3 version could be a nice "instant accelerator" solution for any computer, though. But while USB 3 (barely) matches the eLink bandwidth, an update to the Epiphany there makes it unsuitable again.

[dobkeratops]

The epiphany ISA isn't so far from RISC-V (which is probably why RISC-V is such a natural switch for further evolution of this product line). In terms of educational and development value, concepts will go across quite nicely. (the one difference I can remember offhand (?) is that epiphany has a unified register file whilst RISC-V has more traditional separate float/int registers, but the total number is the same.. 64 vs 32+32. There are a few more quirks but for the main part you'd be coding in C and focussing more on leveraging the special memory architecture.

[eliaskousk]

Hi all,

I have ported RISC-V rocket-chip generated cores (RV64IMA @ 50 MHz and RV64IMAFD @ 25 MHz) on Parallella for my GSoC project.

A bitstream with either of them can boot RISC-V Linux (with RISC-V poky root image) on your Parallella.

You also won't lose any original Parallella functionality since I included everything the original bitstreams provide (E-Link, I2C, GPIO).

The default core without FPU (RV64IMA) boots on all Parallella versions, while the bigger one which contains the FPU (RV64IMAFD) can only fit on the Kickstarter and Embedded versions that have the bigger Zynq device.

You can find the parallella-riscv repo here:

I will soon update with more content the blog where I describe my project:

It would be great if you can test things out (master branch) and if possible report me of any problems you encountered.

Cheers,
Elias

[jar]

Wow, this looks cool!

I want to try this out next week.

[promach]