Whoa, I haven not been following ASM.js stuff in any detail.
Seeing that Metal replaces kernel/userspace boundaries with VM protections for memory, meaning that system call overhead is eliminated, at the price of ASM/VM overhead.
Can someone break this down for me? Looks like it's using... C? to load a js interpreter which bootstraps an API around all UEFI features? Do I have that right?
And, if so, does that mean that once the API has been bootstrapped, one could actually write an OS in js? Or are there other abstractions that would need to be migrated first?
You don't need a JS bootloader to write an OS in JS. The bootloader just drops the machine into some memory address for it to start executing your OS init script. that bit could be a Javascript interpreter. You can't do much with the architecture in Javascript though, because it doesn't allow you to map memory directly to your types (unless there's some ungodly nonesense I'm not aware of) so you'll have to drop into C/asm to e.g. interact with the ports/registers/tables to set up userspace.
Seems like a small number of hobbyists have attempted.
I've heard of people doing this with other high level languages. Basically you need enough low level code to bootstrap a VM. Once you have that, you can make the high level language decide some logic that traditionally would be in C code, like manipulating page tables or whatever.
Automatic Garbage Collection in a kernel probably won't work:
I vaguely remember hearing about someone trying to use .Net in the Windows kernel.
The big problem is garbage collection: If I remember correctly, the fact that "any" operation can fail with an out of memory exception was a huge problem. Another problem was that random pauses for garbage collections in the kernel had major stability issues.
In short, I hope that the js kernel is for amusement and education; otherwise it would need a much more advanced garbage collector then earl 2000's .Net.
> I vaguely remember hearing about someone trying to use .Net in the Windows kernel.
Microsoft did that, it was called Longhorn. That release cycle was long delayed and they abandoned most of its ambitious projects, especially C# in the kernel, and the result was Windows Vista.
GC was not the only reason for the failure of that project. Someone could write a book about it. A lot of it was actually more about the organization of people. I also had heard from insiders that lack of ahead of time compilation was an issue. The other issue I remember hearing about was a complaint that Windows components were not layered cleanly and they ended up with circular dependencies when they tried to rewrite them.
I think it's possible to write a kernel with GC, and to still be judicious about memory usage with a GC language. And I say that as someone who happens to think that a big issue with modern software is that too many programmers are spending their whole education and career to depend on GC without thinking about it carefully. That is to say I'm already a skeptic of high-level languages and GC, but I will still afford that it is technically possible.
You'd need to write an entire hardware abstraction layer to do anything useful. There's projects that do this for microcontrollers - eg MicroPython and Espruino.
I'm pretty sure someone already compiled Linux to asm.js a few years ago. As asm.js is/was a subset of JS, you could say it's already been done. In theory, you could continue work from there in JS.
The choice of Duktape here is smart — it's one of the few JS engines that can actually run freestanding with minimal libc stubs, since it was designed for embedding in constrained environments. V8 or SpiderMonkey would be a nightmare to get running pre-boot.
What I find most interesting is the UEFI services binding approach. Rather than trying to abstract away the hardware, it exposes the raw EFI protocols (GraphicsOutput, SimpleFileSystem, etc.) directly to JS. That's a much more pragmatic design than trying to build a full HAL — you get to prototype UEFI applications rapidly while keeping the escape hatch to C for anything performance-critical.
Would love to see if anyone tries hooking this into UEFI's built-in network stack for PXE boot scripting. That could actually be useful beyond the novelty factor.
Pretty dang common. OS X and macOS (and maybe iOS and iPadOS, though I'm not certain) have been autocorrecting "--" into "—" for over a decade. Windows users have been using Alt codes for them since approximately forever ago: https://superuser.com/q/811318.
Typography nerds, which are likely overrepresented on HN, love both em dash and en dash, and we especially love knowing when to use each. Punctation geeks, too! If you know what an octothorp or an interrobang are, you've probably been using em dashes for a long time.
Folks who didn't know what an em dash was by name are now experiencing the Baader-Meinhof phenomenon en masse. I've literally had to disable my "--" autocorrect just to not be accused of using an LLM when writing. It's annoying.
1) JavaScript must stay in the box (aka in the browser).
2) JavaScript as a general purpose programming language.
While I can absolutely understand 1), I have had wanted to access
the filesystem via JavaScript, just as I do via ruby or python, for
local use only. After I googled for a while, they would say that
this is not possible unless one uses npm/node. I think this shows
that there are use cases here and the "default" JavaScript, aka 1),
does not cover these. I do not like JavaScript, but based on my
own use cases, I actually favour 2) far more than 1). So from that
point of view, being able to access UEFI can also be useful. So
why not.
As for (1) vs (2), it’s not really an issue of JavaScript at all. The main question is, do you want to build something that runs in a browser? If you’re building a web app, you’ll have to use the sandboxed APIs (and probably JavaScript). If you don’t care about the runtime, yeah, you can use Node or Bun or Deno (or use another language altogether).
Does it manage to support floats? I am not sure if those can be safely used in the UEFI environment. (I recall GRUB’s build of Lua being integer-only, and Linux avoiding the use of floating-point arithmetic in kernel mode, but I don’t remember the reason.)
This is hilarious lol, it’ll be any day now before we get a full JS kernel. Garbage collection could be an obstacle, but I know there have been some kernels written in Go/Java before
I don't have real context here, but I can imagine that a platform where the hardware costs millions of dollars, will be booted up in "Production" exactly once, and is guaranteed to be physically destroyed before it hits 1 day of uptime, just "Give it 128GB of RAM and YOLO (literally)" is great advice!
Note: 128GB of DRAM may add another million dollars to the build cost by 2027 at the current derivative of the $/GB curve
I’m always amazed and slightly envious of what programming languages with large developer bases can do. I mean if a language is Turing complete it can do anything, but JavaScript takes this to the extreme.
Mind you I never said anything about quality or performance, obviously doing everything in JavaScript comes with it’s own issues but if you were to say that someone got JavaScript running in the Linux kernel as a POC I wouldn’t even be surprised
Could this be used as a learning tool? Rebooting the computer takes so much more time compared to reloading the browser tab. And you probably can't brick your computer.
webuefi has already been shipped by google for use on chromebooks. but mozilla and apple irrationally refuse to implement the standard for "security reasons"
Why is it a new surface? Either you can run UEFI code, or you can't. Attacking the JS interpreter itself is unrealistic IMHO, it's the poorly written JavaScript running on top of this that might open new surfaces of attack. But other UEFI code is mostly written in C or C++, so let's call that a wash?
Oh hey, we've reached the "Metal" stage! https://www.destroyallsoftware.com/talks/the-birth-and-death...
Whoa, I haven not been following ASM.js stuff in any detail.
Seeing that Metal replaces kernel/userspace boundaries with VM protections for memory, meaning that system call overhead is eliminated, at the price of ASM/VM overhead.
What a fascinating idea. Kidding on the square...
I'm doing my part ∠(‘-‘)
thank u 4 ur serves
Thank you for the reminder to do my yearly viewing of that video lol
Love this. An example of complete and total dominion over the machine. Great quote here too lol
> Prometheus stole fire from the gods and gave it to man. For this he was chained to a rock and tortured for eternity.
Can someone break this down for me? Looks like it's using... C? to load a js interpreter which bootstraps an API around all UEFI features? Do I have that right?
And, if so, does that mean that once the API has been bootstrapped, one could actually write an OS in js? Or are there other abstractions that would need to be migrated first?
You don't need a JS bootloader to write an OS in JS. The bootloader just drops the machine into some memory address for it to start executing your OS init script. that bit could be a Javascript interpreter. You can't do much with the architecture in Javascript though, because it doesn't allow you to map memory directly to your types (unless there's some ungodly nonesense I'm not aware of) so you'll have to drop into C/asm to e.g. interact with the ports/registers/tables to set up userspace.
An OS doesn't need to have a user space :)
> And, if so, does that mean that once the API has been bootstrapped, one could actually write an OS in js?
I bet somebody has done that.
https://www.google.com/search?q=os+kernel+in+javascript
Seems like a small number of hobbyists have attempted.
I've heard of people doing this with other high level languages. Basically you need enough low level code to bootstrap a VM. Once you have that, you can make the high level language decide some logic that traditionally would be in C code, like manipulating page tables or whatever.
Automatic Garbage Collection in a kernel probably won't work:
I vaguely remember hearing about someone trying to use .Net in the Windows kernel.
The big problem is garbage collection: If I remember correctly, the fact that "any" operation can fail with an out of memory exception was a huge problem. Another problem was that random pauses for garbage collections in the kernel had major stability issues.
In short, I hope that the js kernel is for amusement and education; otherwise it would need a much more advanced garbage collector then earl 2000's .Net.
> I vaguely remember hearing about someone trying to use .Net in the Windows kernel.
Microsoft did that, it was called Longhorn. That release cycle was long delayed and they abandoned most of its ambitious projects, especially C# in the kernel, and the result was Windows Vista.
GC was not the only reason for the failure of that project. Someone could write a book about it. A lot of it was actually more about the organization of people. I also had heard from insiders that lack of ahead of time compilation was an issue. The other issue I remember hearing about was a complaint that Windows components were not layered cleanly and they ended up with circular dependencies when they tried to rewrite them.
I think it's possible to write a kernel with GC, and to still be judicious about memory usage with a GC language. And I say that as someone who happens to think that a big issue with modern software is that too many programmers are spending their whole education and career to depend on GC without thinking about it carefully. That is to say I'm already a skeptic of high-level languages and GC, but I will still afford that it is technically possible.
You'd need to write an entire hardware abstraction layer to do anything useful. There's projects that do this for microcontrollers - eg MicroPython and Espruino.
I'm pretty sure someone already compiled Linux to asm.js a few years ago. As asm.js is/was a subset of JS, you could say it's already been done. In theory, you could continue work from there in JS.
https://medium.com/@retrage/lkl-js-running-linux-kernel-on-j...
Depending on your definition of OS, yeah you could do that :)
Hey, when Apple transitioned from m68k to PowerPC, it took them a hell of a long time to rewrite massive parts of their OS. It's a low bar, though...
OS in JS, ok I am interested now...
I presume you'll add the network stack next, so that I can use my favourite, most useful packages?
Well, there's a network stack already there, including HTTP and HTTPS on newer firmwares.
We are getting isOdd in the bootloader before GTA-IV
Wait, when did I time-travel?
oops typo
> If this makes you grin, you are probably holding the torch.
What if it makes me recoil in horror? screams into the void
next step is to create a UEFI TUI using react (please don't)
you may just have casted a curse on our future motherboards, damn you
OMG we can use ink for that
This project will go places. Like every silly project not intended for production. :)
The choice of Duktape here is smart — it's one of the few JS engines that can actually run freestanding with minimal libc stubs, since it was designed for embedding in constrained environments. V8 or SpiderMonkey would be a nightmare to get running pre-boot.
What I find most interesting is the UEFI services binding approach. Rather than trying to abstract away the hardware, it exposes the raw EFI protocols (GraphicsOutput, SimpleFileSystem, etc.) directly to JS. That's a much more pragmatic design than trying to build a full HAL — you get to prototype UEFI applications rapidly while keeping the escape hatch to C for anything performance-critical.
Would love to see if anyone tries hooking this into UEFI's built-in network stack for PXE boot scripting. That could actually be useful beyond the novelty factor.
Are em-dashes really that common to use or did I just start noticing them after LLMs became popular for rewriting comments?
Not implying your comment is LLM generated, clearly it isn't but asking as a genuine question.
Pretty dang common. OS X and macOS (and maybe iOS and iPadOS, though I'm not certain) have been autocorrecting "--" into "—" for over a decade. Windows users have been using Alt codes for them since approximately forever ago: https://superuser.com/q/811318.
Typography nerds, which are likely overrepresented on HN, love both em dash and en dash, and we especially love knowing when to use each. Punctation geeks, too! If you know what an octothorp or an interrobang are, you've probably been using em dashes for a long time.
Folks who didn't know what an em dash was by name are now experiencing the Baader-Meinhof phenomenon en masse. I've literally had to disable my "--" autocorrect just to not be accused of using an LLM when writing. It's annoying.
⌥- produces a – as well. That's sometimes easier than typing `--` and hoping for the best.
It really is. We dash-users are the real and most important victims of the AI revolution. I hope someday our story will be told (by the machines)
I think there are two philosophies here:
1) JavaScript must stay in the box (aka in the browser).
2) JavaScript as a general purpose programming language.
While I can absolutely understand 1), I have had wanted to access the filesystem via JavaScript, just as I do via ruby or python, for local use only. After I googled for a while, they would say that this is not possible unless one uses npm/node. I think this shows that there are use cases here and the "default" JavaScript, aka 1), does not cover these. I do not like JavaScript, but based on my own use cases, I actually favour 2) far more than 1). So from that point of view, being able to access UEFI can also be useful. So why not.
> I have had wanted to access the filesystem via JavaScript, just as I do via ruby or python
There are some (limited) ways to do so now: https://developer.mozilla.org/en-US/docs/Web/API/File_System...
As for (1) vs (2), it’s not really an issue of JavaScript at all. The main question is, do you want to build something that runs in a browser? If you’re building a web app, you’ll have to use the sandboxed APIs (and probably JavaScript). If you don’t care about the runtime, yeah, you can use Node or Bun or Deno (or use another language altogether).
Try webkitdirectory file attribute for browser access to the file system.
Wow, this is cursed.
I think the proper term is blursed.
I think r/unixporn will love it once it gets DOM support :^)
Finally, we can create splash screen animations in pure CSS!
"The Birth and Death of JavaScript" is coming true after all.
I was going to post this as well! A direct link to the video: https://www.destroyallsoftware.com/talks/the-birth-and-death...
This is both so impressive and cursed that I'm not sure how to feel.
Does it manage to support floats? I am not sure if those can be safely used in the UEFI environment. (I recall GRUB’s build of Lua being integer-only, and Linux avoiding the use of floating-point arithmetic in kernel mode, but I don’t remember the reason.)
Floating point was not supported in the Linux kernel to avoid having to save/restore FP registers.
Yeah floats works
This is hilarious lol, it’ll be any day now before we get a full JS kernel. Garbage collection could be an obstacle, but I know there have been some kernels written in Go/Java before
It could be even better!
https://en.wikipedia.org/wiki/Java_processor
Who needs to garbage collect? Just leak memory until the system dies! That strategy seems to be good enough for claude code, anyway.
If it’s good enough for missile guidance systems, it’s good enough for me.
I don't have real context here, but I can imagine that a platform where the hardware costs millions of dollars, will be booted up in "Production" exactly once, and is guaranteed to be physically destroyed before it hits 1 day of uptime, just "Give it 128GB of RAM and YOLO (literally)" is great advice!
Note: 128GB of DRAM may add another million dollars to the build cost by 2027 at the current derivative of the $/GB curve
Turning in the widening gyre, the falcon cannot hear the falconer. The center cannot hold.. The old prophecy is coming true.
I’m always amazed and slightly envious of what programming languages with large developer bases can do. I mean if a language is Turing complete it can do anything, but JavaScript takes this to the extreme.
Mind you I never said anything about quality or performance, obviously doing everything in JavaScript comes with it’s own issues but if you were to say that someone got JavaScript running in the Linux kernel as a POC I wouldn’t even be surprised
Could this be used as a learning tool? Rebooting the computer takes so much more time compared to reloading the browser tab. And you probably can't brick your computer.
Can't wait for browser support for this... ;-)
webuefi has already been shipped by google for use on chromebooks. but mozilla and apple irrationally refuse to implement the standard for "security reasons"
Soon™
Yeah, but your [developers] were so preoccupied with whether or not they could, they didn't stop to think if they should.
This is incredible.
> If this makes you grin you are probably holding a torch
Hilarious
Your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should!
Awesome! Everything will be rewritten in JS
"Your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should."
Pretty neat, though.
It begins!
Finally!
I love it.
But why?
It's just a silly experiment; the real endgame is to make a bootloader that is customisable using HTML/CSS/JS
Since PDFs can contain JS, presumably that should be the preferred way of modifying your boot loader.
Yeah that's the natural next step, I'll work on that next
Why not?
Because this can end very badly. It is a new surface to attack
Exactly! It's actually great! More ways to jailbreak stuff.
Why is it a new surface? Either you can run UEFI code, or you can't. Attacking the JS interpreter itself is unrealistic IMHO, it's the poorly written JavaScript running on top of this that might open new surfaces of attack. But other UEFI code is mostly written in C or C++, so let's call that a wash?
Maybe? What's your threat model?
Cursed