m1n1 VS linux

One of the coolest things (IMO) about the entire Asahi effort, and why I'm not at all surprised that they surpassed Apple, was the dedicated effort to build bespoke developer-friendly Python tooling early in the reverse engineering process.

https://asahilinux.org/2021/08/progress-report-august-2021/

> Since the hypervisor is built on m1n1, it works together with Python code running on a separate host machine. Effectively, the Python host can “puppeteer” the M1 and its guest OS remotely. The hypervisor itself is partially written in Python! This allows us to have a very fast test cycle, and we can even update parts of the hypervisor itself live during guest execution, without a reboot.

> We then started building a Python implementation of this RPC protocol and marshaling system. This implementation serves a triple purpose: it allows us to parse the DCP logs from the hypervisor to understand what macOS does, it allows us to build a prototype DCP driver entirely in Python, and it will in the future be used to automatically generate marshaling code for the Linux kernel DCP driver.

Code here: https://github.com/AsahiLinux/m1n1/blob/main/proxyclient/m1n...

If you watch any of Asahi Lina's streams from the time before they had working drivers, she's able to weave together complex bitflag-manipulating pipelines at the speed of thought with self-documenting code, all in Python running on the host machine, all while joking with viewers via her adorable avatar. I've never seen anything like it before. The whole workflow is a tremendous and unprecedented accomplishment by the entire Asahi team.

I wrote a m1n1 experiment to test IRQ delivery in EL1 and noticed something was weird. I already knew about that IRQ control register (3 masks IRQs entirely and is the default, that whole thing took like a day or two back when I first added M1 Pro/Max support), so I tried other values and 2 fixed it.

They have not dropped hardly any official documentation on iBoot. The best safe documentation is in: https://github.com/AsahiLinux/m1n1/ There's a lot of tainted docs out there because the source to iBoot was illegally leaked a while back, but marcan is known for being a bit of a hardass when it comes to legal reverse engineering (thankfully).

No its uefi boot manager “https://github.com/AsahiLinux/m1n1 “

What makes you say there isn't community participation? The repo for m1n1, at least, has 42 contributors according to Github[1]. There's plenty more reporting bugs and such, and their IRC channel seems relatively active.

1: https://github.com/AsahiLinux/m1n1

I can confirm that’s pretty much exactly what happens. I did some digging with the help of m1n1 a while back, and essentially yeah, this is almost exactly what it does. The only difference is that, rather than tracking which cores are running emulated code, the scheduler keeps track of which processes are running in emulation mode, and prior to returning to userland after a context switch, the kernel sets control register bits for features like TSO (which is what I was interested in looking into at the time; I believe that specifically is controlled somewhere in the actlr_el1 register). Although only the P-cores actually implement the necessary x86 emulation behavior, the scheduler of course wants to ensure that a process is not pinned to any one core, and that native and emulated processes alike can preempt and interleave with each other on the P-cores just as they would if there were no emulation.

That shim/stub is m1n1. It is the bootloader for Asahi Linux, but also makes it possible to talk to the hardware over USB as just described by Lina. marcan even implemented a small hypervisor in m1n1, so it can be used to run MacOS and trace how MacOS is accessing the hardware.

Windows 11 ARM dualboot will come to M1 macs in the near future. See m1n1 for progress.

You're missing on a lot of things Rust (or any language with non-toy types) can provide. Lock ordering, better accessible complex structures, enforcement of enumerated options, rich description of APIs, and many others. Atomic values are usable transparently https://github.com/AsahiLinux/linux/blob/97c628055904a7f2ef1... and multithreaded reference counting is easily enforced https://github.com/AsahiLinux/linux/blob/bd0a1a7d465fcb60685... also issues like type confusion https://www.vicarius.io/vsociety/posts/a-type-confusion-bug-... are less likely if you can easily use tagged unions checked by the compiler.

From the gpu issue tracker[0]:

> For a bit of context -- Google Maps loads images to the GPU at.. inopportune times. While games would typically load their images during a load screen (so slow image loading just means longer loading screens), Google Maps loads when scrolling around I think (so slow image loading means the whole map stutters). I don't think there's a fundamental driver bug we can fix here, but we can make image loading a lot faster which makes the symptoms go away.

[0]: https://github.com/AsahiLinux/linux/issues/72#issuecomment-1...

> Is this mostly just a thing to get more young people interested in kernel development...allowing them to start out in less important areas and in a language they are passionate about?

Not likely. At the moment you need to do extra work to get Rust working well. It's not exactly beginner friendly and doing work in the kernel, you'll need to dig into C anyway.

> Or is this a serious proposal about the future of operating systems and other low level infrastructure code?

Serious code already exists, so... Yes?

> Do you just program everything in unsafe mode? What about runtimes?

Why would you? You need that only when interfacing with something that can't hold the Rust compiler assumptions. See for example https://github.com/AsahiLinux/linux/blob/gpu/rebase-6.4/driv...

The few places that need direct access / unsafe are almost all single-line areas with an explanation.

I think the idea with the M-series laptops in particular is that you can drive the speakers at volumes that actually damage them very quickly ( see https://github.com/AsahiLinux/linux/issues/53 ). The idea AIUI is that you can use a DSP along with a physical model of the voice coil to get better sound than you would if the speakers were volume-limited.

I am using Asahi Linux and the GPU driver works great, it even supports OpenGL 3.1 (https://asahilinux.org/2023/06/opengl-3-1-on-asahi-linux/). Definitely not alpha, I would say it's close to a "release candidate". Many bugs got resolved, nothing much left (besides newer OpenGL and Vulkan of course, but current state is very stable): https://github.com/AsahiLinux/linux/issues/72

There aren't really any non-trivial mainline modules, since the Rust support is so new. There's the non-mainline Asahi M1 GPU driver though! It will eventually be mainlined, but IIRC some more Rust support code needs to be mainlined first.

https://github.com/AsahiLinux/linux/tree/asahi/drivers/gpu/d...

You can follow the progress here: https://github.com/AsahiLinux/linux/issues/91