The HiFive Unleashed is interesting in that it has a lot more RAM than cheap ARM dev boards, for the same money though I could get a HoneyComb LX2K ARM system.
HiFive Unleashed is $1000 for the board with onboard RAM… but it does not have PCIe onboard, so if you want that, you could pay $2000 extra (!!) for the "HiFive Unleashed Expansion Board" that has a giant FPGA that has a PCIe root complex programmed on it.
HoneyComb LX2K is $750 for the board with 64GB eMMC + bring your own SODIMMs for RAM.
SolidRun also offers the MACCHIATObin for $339. 4-core A72 + 4GB full-size DIMM included. (The single-channel-ness of the RAM is not good for performance, but you can install a big 16GB DIMM no problem.) Both the LX2K and the mcbin have PCIe of course :)
> If you want to do any OS work, you need a system that implements the Privileged ISA. Supporting the Privileged ISA is synonymous to being able to run UNIX-like systems, because it brings user-/supervisor-mode distinction and paging. Working on real hardware is generally preferred to working in emulators, because the code eventually has to run on metal anyway and emulators can be too forgiving for certain classes of problems. There is a plethora of RISC-V microcontrollers for a couple of dollars that all don’t support the Privileged ISA. At the time of writing, the only board you can buy that does support it is the $1000 HiFive Unleased, which was beyond my “I just want to play around with this” budget.
Suggests to me that it's at least part of why Stephen Marz [0] isn't trying to target a specific board with his project (which has been posted here a few times and I'm sorta following along). That pretty much kills most of the interest in RISC-V that I had in me.
I guess I'll wait a few more years and check back again later.
[0]: https://osblog.stephenmarz.com/index.html