xv6-riscv VS hubris

okay, fair. i only got misled by the title of the post, which claims all-rust xv6 port.

now that we cleared the userland part, here’s what I’m contemplating on the kernel side. i can’t think of anything simpler and more staple than this, so:

https://github.com/dancrossnyc/rxv64/blob/main/kernel/src/ua...

https://github.com/mit-pdos/xv6-riscv/blob/riscv/kernel/uart...

honestly - i don’t feel at ease to tell which driver code is more instructional, which is easier to read, which is better documented, which is better covered with tests, which has more unsafety built into it (explicit or otherwise), what size are the object files, and what is easier to cross-compile and run on the designated target from, say, one of now-ubiquitous apple silicon devices.

lest we forget that the whole point of it is “pedagogical”, i.e. to learn something about how a modern OS can be organized, and how computer generally works.

and i’m just not sure.

The x86 version of xv6 is no longer updated, the last updates took place about 7 years ago. Current xv6 supports RISC V in qemu, there are also ports to real RISC V devices (Kendryte/Canaan K210, Allwinner D1, StarFive JH7110, some hacked by me) and FPGA implementations ().

  https://github.com/mit-pdos/xv6-riscv/ (qemu)

I am no help with recruitment, but simple search revealed "https://github.com/mit-pdos/xv6-riscv", were you aware of this?

Different repo under same org https://github.com/mit-pdos/xv6-riscv

I'm reading through the MIT xv6 OS handbook and code (here: https://github.com/mit-pdos/xv6-riscv/) and they mention the fact that they created it as a monolithic kernel since most unix systems are monolithic. They then introduce the microkernel concept. Are there microkernel concepts out there (especially code) I can check out? I'm curious to see how userspace processes communicate to kernel processes to execute privileged actions.

Yeah its from here: https://github.com/mit-pdos/xv6-riscv x86 version here: https://github.com/mit-pdos/xv6-public

I would start with working through an OS textbook. Tanenbaum is highly regarded although I worked through OStep and I felt it was very approachable. Also check out wiki.osdev.org. Also, here's a re-inplementation of Unix version 6. I've been meaning to play around with it for a while.

NOTE: we have stopped maintaining the x86 version of xv6, and switched our efforts to the RISC-V version (https://github.com/mit-pdos/xv6-riscv.git)

> The CPUs in Oxide racks are AMD, so, presumably AMD-based compute rather than ARM.

These don’t run Hubris though; based on the chips directory in the repo [0], they’re targeting a mix of NXP and ST parts, which are Arm, and the user isn’t likely to see them or care what firmware they’re running: they’re really pretty “boring”.

[0] : https://github.com/oxidecomputer/hubris/tree/020d014880382d8...

I wouldn't put this comment here. It's not just some detail of this function; it's an invariant of the field that all writers have to respect (maybe this is the only one now but still) and all readers can take advantage of. So I'd add it to the `TaskDesc::regions` docstring. [1]

[1] https://github.com/oxidecomputer/hubris/commit/b44e677fb39cd...

With respect to Hubris, the build badge was, in turns out, pointing to a stale workflow. (That is, the build was succeeding, but the build badge was busted.) This comment has been immortalized in the fix.[0]

With respect to Humility, I am going to resist the temptation of pointing out why one of those directories has a different nomenclature with respect to its delimiter -- and just leave it at this: if you really want to find some filthy code in Humility, you can do much, much better than that!

[0] https://github.com/oxidecomputer/hubris/commit/651a9546b20ce...

A lot of questions in there! Taking these in order:

1. We aren't making standalone servers: the Oxide compute sled comes in the Oxide rack. So are not (and do not intend to be) a drop in replacement for extant rack mounted servers.

2. We have taken a fundamentally different approach to firmware, with a true root of trust that can attest to the service processor -- which can turn attest to the system software. This prompts a lot of questions (e.g., who attests to the root of trust?), and there is a LOT to say about this; look for us to talk a lot more about this

3. In stark contrast (sadly) to nearly everyone else in the server space, the firmware we are developing is entirely open source. More details on that can be found in Cliff Biffle's 2021 OSFC talk and the Hubris and Humility repos.[0][1][2]

4. Definitely not vaporware! We are in the process of shipping to our first customers; you can follow our progress in our Oxide and Friends podcast.[3]

[0] https://www.osfc.io/2021/talks/on-hubris-and-humility-develo...

[1] https://github.com/oxidecomputer/hubris

[2] https://github.com/oxidecomputer/humility

[3] https://oxide-and-friends.transistor.fm/

everywhere, for example in https://github.com/oxidecomputer/hubris/search?q=dyn

Is Box really allocating here? Is the "Rust By Example" text incomplete?

Then I had to stop learning Rust for other reasons, but this doubt really hit me at the time.

I work on an embedded OS in Rust (Hubris) that has a very bespoke build system. As part of the build system, it has to set environmental variables based on (1) the target device and (2) the specific "task"; this is an OS with task-level isolation, so tasks are compiled as individual Rust crates.

Oxide Computer told some storied about the difficulty of bring up of a new motherboard, and mentioned a lot of gotcha details and hack solutions for managing their AMD chip.

They talked about their bring up sequence, boot chain verification on their motherboard, and designing / creating / verifying their hardware root of trust.

I heard mention of this on a podcast recently, trying to find the reference.

I'm pretty sure it was [S3]

- "Tales from the Bringup Lab" https://lnns.co/FBf5oLpyHK3

- or "More Tales from the Bringup Lab" https://lnns.co/LQur_ToJX9m

But I found again these interesting things worth sharing on that search. https://oxide.computer/blog/hubris-and-humility, https://github.com/oxidecomputer/hubris

Search 1 [S1], Trammell Hudson ep mentioning firmware (chromebook related iirc) https://lnns.co/pystdPm0QvG.

Search 2 [S2], Security, Cryptography, Whatever podcast episode mentioning Oxide and roots of trust or similar. https://lnns.co/VnyTvdhBiGC

Search links:

[S1]: https://www.listennotes.com/search/?q=oxide+tpm

[S2]: https://www.listennotes.com/search/?q=oxide%20and%20friends%...

[S3]: https://www.listennotes.com/search/?q=oxide%20and%20friends%...

When we started the company, we knew it would be a three year build -- and indeed, our first product is in the final stages of development (i.e. EMC/safety certification). We have been very transparent about our progress along the way[0][1][2][3][4][5][6][7] -- and our software is essentially all open source, so you can follow along there as well.[8][9][10]

If you are asking "does anyone want a rack-scale computer?" the (short) answer is: yes, they do. The on-prem market has been woefully underserved -- and there are plenty of folks who are sick of Dell/HPE/VMware/Cisco, to say nothing of those who are public cloud borne and wondering if they should perhaps own some of their own compute rather than rent it all.

[0] https://oxide-and-friends.transistor.fm/episodes/holistic-bo...

[1] https://oxide-and-friends.transistor.fm/episodes/the-oxide-s...

[2] https://oxide-and-friends.transistor.fm/episodes/bringup-lab...

[3] https://oxide-and-friends.transistor.fm/episodes/more-tales-...

[4] https://oxide-and-friends.transistor.fm/episodes/another-lpc...

[5] https://oxide-and-friends.transistor.fm/episodes/the-pragmat...

[6] https://oxide-and-friends.transistor.fm/episodes/tales-from-...

[7] https://oxide-and-friends.transistor.fm/episodes/the-sidecar...

[8] https://github.com/oxidecomputer/omicron

[9] https://github.com/oxidecomputer/propolis

[10] https://github.com/oxidecomputer/hubris