[JoachimSchipper]

Having an actual RISC-V ASIC is cool, but note that you can run a RISC-V softcore on a significantly cheaper FPGA board - or even in software simulation.

This is more interesting for showing progress in the RISC-V ecosystem than for hacking around with.

[aseipp]

Honestly, if you want a full MMU with a Linux-capable RISC-V implementation and everything, and a few cores like this -- you'll need a fairly decent FPGA, as well as the clocking resources/peripherals so things aren't unusably slow. You can get cheap FPGAs for the microcontroller-class devices/cores, but the FPGAs SiFive recommend for U-series cores of theirs are quite expensive, like $4000. lowRISC can run on something like a $1500 Kintex-7 devkit, I think. There are better boards coming out soon at better price points (such as this one[1]) that might fit the bill, but then you have to do board setup yourself... It's not worth it IMO unless you plan on reusing the FPGA.

If you want a microcontroller class chip so you can just play with the 32-bit instruction set -- you can get that with QEMU and a $60 HiFive1 board. You can run picorv32 on a $50 FPGA, even! But if you want a Linux-class chip now (with full features you expect e.g. from an ARM-class device) -- this is about as good as it gets, I think. You won't get a 1.5ghz quad core performance like that cheaply. For now. Next year it'll be different, hopefully.

I imagine the real reason this board is pricey is due to limited volume runs for the ASIC on 28nm, which is the bulk (how many people will really buy one? these are early adoption systems), and, I speculate, some of the weird material choices. 8GB DDR4 ECC, ok sure that's cool and unique, but no SATA port? Really, so I'm stuck on a stupidly large microSD card? And they specify FMC, but FMC cards are typically very expensive for high-throughput devices (think HDMI, ADC/DACs, SFP/SFP+ breakouts). Maybe they'll just go all out and have the FMC mount the system directly onto a broken-out PCIe carrier board, or something? I dunno.

As for hacking... all that said, the rather large amount of RAM and relatively fast cores do excite me -- it means you can actually use the parallelism offered for things like actual compilation. And it's real privileged silicon, so for system porters/distros/etc I think it's probably more reasonable of a purchase. I'm eager to get NixOS running on a real silicon device like this, so I've supported it (I had a lot of fun with my HiFive1). If they had just included SATA, this would be almost a no-brainer for integrators/distro porters. I just hope they'll follow up on a decent expansion option... In the mean time until it ships, QEMU should be ironed out enough by now to start a real port...

[1] https://shop.trenz-electronic.de/en/TEF1001-01-Kintex-7-PCIe...

[jackckang]

Your speculation is quite accurate...there will be FMC expansion cards specifically built for the HiFive Unleashed that will break out most of those peripherals you're talking about (PCIe, SATA, to name a few in particular). Unfortunately we weren't quite ready to announce those details today but will be making those updates ASAP.

The reason for the large RAMs and microSD card is specifically to help software developers. That's who the board is for until we can drive the cost down even further for even more folks.

-Jack Kang, SiFive

[aseipp]

Thanks for the confirmation! The microSD card's speed is my main complaint, relative to everything else. But I'm just complaining I guess -- because otherwise I think the board looks very good, without any expansions. :)

It seems every board always has a catch somewhere, but if an FMC expansion can work around this, that'd be excellent. I'm looking very forward to putting this machine through its paces once I get my hands on it!

[rwmj]

Without the expansion board you'd likely use iSCSI or NFS root for the OS. The SD card would only be used to boot.

[Nexxxeh]

Gigabit ethernet though, so network storage is presumably an option. The Pi suffers from relatively poor network throughput (although much improved since the first release way back when)but I'm assuming this won't suffer the same problems.

[makomk]

There's already a plethora of cheap Pi-like boards out there from various companies with gigabit ethernet that's not USB-based and other nice features, many of which have the advantage of having more established software support. If you're willing to give up features like graphics which this board also lack, you can even have a 100% open source software stack on them.

[jeanmichelx]

I guess that implementing SATA for a small batch of board would have been cost-prohibitive. SATA isn't simple.

[aseipp]

The board is already cost-prohibitive for most people! They probably lose money on these alone -- the tape-out for a 28nm ASIC is millions alone, they're never getting that back off niche development kits.

Plus, given it has a custom ASIC and rather newer components like DDR4 (DDR4 controllers aren't exactly trivial on their own) and FMC (not simple, high cost), I'm having a hard time feeling sympathetic for this particular complaint, especially considering bottom-of-the-barrel boards like the OrangePi & networking competitors like MacchiatoBin can stack in multiple SATA ports on devices in the $50 to $350 range.

I mean, the board is already $1k, and I doubt they're going as far as home grown USB/UART/JTAG chips -- probably FTDI chips, so some of the open hardware claim is a bit fluff in practice, I'm guessing (I don't think this is a huge deal, but many people do). You'd probably use an off the shelf SATA controller & chip, it's not like you really get a lot from rolling your own.

Then again, I've never taped out a board with SATA, so what do I know? But I find it hard to believe the difficulty/cost of acquiring the chip/controller, or integrating it, is a limiting factor in a run like this. Unless they actually planned on rolling it themselves, and I don't know why they would. I'm honestly guessing they're just leaving it to expansions for whatever reason, but we'll see.

[jabl]

See slide 38 in the slide link at https://fosdem.org/2018/schedule/event/riscv/

It mentions low speed peripherals like UART being open source, but high speed interfaces like DDR and ethernet are 3rd party licensed IP blocks.

[garmaine]

The FPGA boards capable of running a U54 image (what this dev board is) are much more than $1k. And the resulting clock rate would be orders of magnitude less.

That said, FPGA boards are useful for doing interesting things with RISC-V, such as writing custom accelerators.

[greglindahl]

It all depends on what you're doing. If you make do with pure software, you should stay there. But if you want to execute a lot of instructions, for example to use CRASHME or descendant to look for bugs in the cpu implementation or Linux or whatever, being able to execute several orders of magnitude more instructions by paying more for an ASIC can be very worthwhile.

And before you think this is a silly example, I found a bug in a new microprocessor once using CRASHME. I was attempting to evaluate the quality of the supplier's testing.

[jacquesm]

> I was attempting to evaluate the quality of the supplier's testing.

That looks like mission accomplished to me.