by brucehoult | 2025-04-24 02:19:00+00:00
> In 5 years they went from the HiFive Unmatched on 5nm

It's 28nm.

> the HiFive Premier on 7nm

The EIC7700X is on TSMC 12 nm FFC.

You're not doing well on the easily googleable facts here.

Also the HiFive Unmatched (may 2021) uses prototype shuttle-run chips, while the Premier (December 2024, 3 1/2 years not five) uses mass-production chips.

A more accurate comparison would be either from the Unmatched to IBM's "Horse Creek" prototype board demoed in September 2023 (2 1/4 years apart) or else from the VisionFive 2 (February 2023) to the Premier, which is 1 3/4 years.

So your five years is way out too.

> current [RISC-V] products don't include anything that runs faster than QEMU

Current RISC-V does fine compared with QEMU on a Mac/PC, at least on a per core basis.

Note that all the following use qemu-user effectively in a chroot (docker), which is much faster than full-system emulation using qemu-system.

Let's take compiling the Linux kernel, commit 7503345ac5f5 from early December, with defconfig, oldish now but I'm sticking with it for my benchmarks to keep them comparable:

RISC-V Hardware

6m42s: Milk-V Pioneer, 64x C910 42m12s: Milk-V Megrez, 4x P550 60m17s: Milk-V Pioneer -j4 67m35s: VisionFive 2, 4x U74 70m57s: Lichee Pi 3A, 8x x60 88m04s: Lichee Pi 4A, 4x C910

Docker/qemu-user:

19m13s: i9-13900HX, 8P + 16E cores, 32 threads 48m37s: i9-13900HX, -j4 69m16s: Mac Mini M1, 4P + 4E cores 143m20s: Ryzen 5 4500U, 6x Zen2 251m31s: i7-3720QM (4x Ivy Bridge)

The 24 core i9 (which can compile a native x86_64 version of the same kernel in 1m3s) takes three times longer using qemu than the fastest current RISC-V machine, which has a similar list price. It's twice as fast as a $199 4 core RISC-V (Megrez).

When restricted to -j4, the i9 with qemu takes 15% longer than the quad core $199 RISC-V SBC.

The i9 is good if you already have it and it's under-utilised, but if you are buying something for dedicated use then you'll get much more RISC-V build speed from the Pioneer, or the same from two $199 boards or four $50 boards (either Orange Pi RV or RV2, for example, which are the same SoCs as my older VisionFive 2 and Lichee Pi 3A respectively).

If you're using an M1 Mac then qemu on it is in the pack with the cheap RISC-V boards, and well behind the P550 boards.

I bought the Ryzen 4500U at the same time as the M1 Mac (both in late 2020). It's a pleasant machine, but really doesn't cut it for running qemu. Neither does the 2012 Ivy Bridge machine -- I remember thinking a 3770 was hot stuff, and the 3720 won't be far off it (3.6 turbo vs 3.9 turbo)

> If they had by now a dev board that was $2000, consumed 300w and crashed if you looked at it funny, that would be better than what we have now

But we've had such a machine -- the Milk-V Pioneer -- for 15 months already. It's $1500 for the board, or $2500 for a fully built machine in a case with power supply, 128 GB RAM, 1 TB SSD, AMD GPU card. It uses 90W when loaded down (not 300) and 68W when idle.

Perhaps you missed the story where Chimera Linux announced on March 12 that they were dropping RISC-V support for lack of a suitable build machine, someone gave them access to their Pioneer, and on March 20 they said they'd done a successful full build of their entire distro (there are 11,057 packages in their repo) and weren't dropping RISC-V after all. It took a few days to get access to the machine, a few days to get set up on it, and ... well we don't know how long the build took, but it's whatever is left from 8 days elapsed ... minus however long it took to write the 2nd blog post.