XiangShan VS seL4

Are you calling for the government to pick a winner? The Chinese word for this fierce if at times chaotic competition is "juan". It worked for them in EV and PV. The outcome remains to be seen in chips and commercial space launches. But even their mostly (ex-)students-run open source Xiangshan RiscV project https://github.com/OpenXiangShan/XiangShan shows a remarkable level of sophistication.

> Certainly no RISC-V implementations that are in the hands of customers right now do any fusion and it doesn't seem to hurt their ability to match or exceed the performance of similar Arm cores (A55, A72).

You can play around with OpenXianShan though, they have a few fusion targets: https://github.com/OpenXiangShan/XiangShan/blob/master/src/m...

Most of the targets require the same destination, so it won't be able to fuse current codegen. I suppose there is still some time before compilers need to be ready, but it's not that much.

> Perhaps they will provide compiler patches if required.

I hope so, btw t-head seems to be still be trying to upstream XTheadVector: https://gcc.gnu.org/pipermail/gcc-patches/2024-January/64278...

This is the most advanced open source risc-v implementation I'm awair of: https://github.com/OpenXiangShan/XiangShan

Maybe implement a big feature for a open source design? like vroom or xiangshan.

I did know about XiangShan, but not Aolai. Is it a Linux distribution?

If you are interested in high performance look into vroom , c910 and xianghan, maybe you could adopt one of them.

> People like to snob Unix but the fact is: the world runs on Unix.

The world you are aware of runs on it.

> Can we really do that much better or is it just hubris?

Yes. Have a look at seL4[1] and Barrelfish too[2], even though that's no longer active. seL4 in particular is powering a lot of highly secure computing systems. There is a surprisingly large sphere outside of Unix/POSIX.

[1] https://sel4.systems/

[2] https://barrelfish.org/

There are also RTOS-capable microkernels such as seL4[0], with few but extremely fast syscalls[1]. Note times are in cycles, not usec.

0. https://sel4.systems/

1. https://sel4.systems/About/Performance/

https://sel4.systems

Working on a number of platforms, verified on some. Multicore support is an ongoing effort afaict.

On OS built on this kernel is still subject to some assumptions (like, hardware working correctly, bootloader doing its job, etc). But mostly those assumptions are less of a problem / easier to prove than the properties of a complex software system.

As I understand it, guarantees that seL4 does provide, go well beyond anything else currently out there.

Take a look at this: https://sel4.systems/

It's probably have to be seL4 (https://sel4.systems), running on some fully OSS hardware.

There are question marks over much of available RISC-V chips due to chinese producers, so maybe OpenPower based hardware?

Plus, the entire system (motherboard, etc) would need to be manufactured using a good supply chain.

Hmmm, this has probably all been thought through in depth before by others. :)

You can use it to (mostly) validate small snippets are the same. See Alive2 for the application of Z3/formalization of programs as SMT for that [1]. As far as I'm aware there are some problems scaling up to arbitrarily sized programs due to a lack of formalization in higher level languages in addition to computational constraints. With a lot of time and effort it can be done though [2].

1. https://github.com/AliveToolkit/alive2

2. https://sel4.systems/

Formal methods. This is not in most general-purpose programming languages and probably never will be (maybe we'll see formal methods to verify unsafe code in Rust...) because it's a ton of boilerplate (you have to help the compiler type-check your code) and also extremely complicated. However, formal methods is very important for proving code secure, such as sel4 (microkernel formally verified to not have bugs or be exploitable) which has just received the ACM Software Systems Award 3 days ago.

Today we'd look at seL4.