Have noodled around with a side-project generating an entire system from boot loader via LLMs but haven't had energy for it given job is the same headspace that needs to be ignored once in a while to not burnout; ultimately want to boot a model of my Linux use (am using bpf to plan and model everything possible and convert it to a compute schedule for sched_ext) and just have a kernel <> model architecture
For security am considering how to embed in the model various authentication obligations to block access to certain blocks of memory without confirmation via webcam and key or something
I think "leveraged this coding methodology" is an unjustifiably positive way to describe the results of the process. I think "spread this disease" would be more accurate. UTF-16 strings, really? VFAT? PE32+ is maybe justifiable (I'd prefer ELF, but that's because it's more familiar, not because it's actually better), but VFAT? And even in 01998 it should have been apparent that UTF-16 was not a sane format for strings, much less in 02005 when the EFI → UEFI transition happened.
To me, UEFI is like "leveraging the waste disposal methodology" of dumping your toxic waste in a lake. Yes, it's more convenient for you, but it does lasting damage and causes years of suffering for millions of people; and eventually somebody else has to clean up your mess, at far greater cost than if you'd just done something sensible to begin with.
I could probably say the same thing about X-Windows.
I've never _actually_ implemented a filesystem, but when researching OS dev it seemed like FAT32 was pretty close to what you'd write as a minimum viable filesystem while being a very well known quantity.
Yes, I think that's a fair assessment, although the fractal of stupid runs deep in FAT32: a separate 5-bit field for seconds within a minute? Separate fixed-width fields for filename and extension? A 4 GiB file size limit?
But, although FAT32 does indeed have the virtue of relative simplicity, that's no excuse for VFAT.
In the eternal words of the Microsoft Game Development Kit docs[0], "Windows operates natively in UTF-16 [...]. This is a unique burden that Windows places on code that targets multiple platforms."
I wonder when Microsoft will stop being a "UTF-16 house" adding UTF-16 to new projects... They did it again to LSP, and that was in 2016. Maybe by 2045 Microsoft will use UTF-8 for new projects, and then by 2100 we can switch to UTF-8 by default.
That one is explainable by the fact that it was developed for VS Code, a typescript/javascript project. Javascript uses UTF-16 for strings (for historical reasons unrelated to Microsoft, though they are the same reasons that made MS use UCS-2 during the same time period).
> UTF-16 is used by the Windows API, and by many programming environments such as Java and Qt. The variable-length character of UTF-16, combined with the fact that most characters are not variable-length (so variable length is rarely tested), has led to many bugs in software, including in Windows itself.
Absolutely, UTF-16 is bad and inexcusable in most contexts. Perhaps you misinterpreted my comment or I wasn't expressing myself properly.
I was trying to say: If all the components in your stack are javascript-based, it makes sense that your RPC-API would also use UTF-16. It wasn't Microsoft pushing it for historical Windows reasons as GP implied, it was dictated by a JS stack they chose but didn't create.
> The linker won’t complain if your code calls functions that don’t exist – it will just mark them as external, expecting them to be provided by some other code. But they won’t be, and the program will just crash when it calls one of these missing functions.
You can verify no external symbols remain after linkage with: nm -D --undefined-only. This can be incorporated into a build script to verify the binary is valid.
This guide is fantastic for getting rolling in the UEFI space. I used this as one of the references when building a bootloader with Zig. Has its own set of issue, especially that 16bit character situation.
Once you dig into those there are a bunch of sharp edges, or maybe it's just that that EFI environment is so weird compared to typical Linux system or application development.
I was pleased last week that I could elicit enough of a UEFI environment from Opus 5.5 to be able to build an UEFI application without enormous, un-auditable dependencies like gnu-efi. Claude distilled the relevant parts of the UEFI interface into a 289-line header file. The example application just displays the keyboard and mouse events on a UEFI framebuffer using a vendored pixel font, thus the name "inputmon": http://canonical.org/~kragen/sw/inputmon-3.tar.gz
The Makefile includes a "run" target to boot it under QEMU with the OVMF implementation of UEFI.
(One fairly surprising feature of all this is that, not counting the time Claude was waiting for me, it took the model a total of about 7 minutes to write and test this. These 7 minutes were spread over almost 15 hours because I ran out of tokens and spent time thinking. This might be a good example of a case where an LLM is literally a million times more productive than a human programmer: the task is algorithmically trivial, and it doesn't involve difficult engineering tradeoffs, but involves deep knowledge of a pile of obfuscated recondite interfaces that are publicly documented and widely used by published open-source software. It is something I've wanted to do for 7 million minutes.)
I'm hoping I can get an in-browser demo of inputmon working next week, but that's probably going to involve doing some surgery on Bochs in order to get an amd64-compatible virtual machine that doesn't require multithreading the way QEMU does.
Inputmon does have the enormous, un-auditable dependency of LLVM and Clang, but that's a horror I'm already resigned to. But with clang, lld, and make, you can build the image from source, and with QEMU and OVMF you can run it in a virtual machine.
I think it's a little bit debatable to call UEFI "bare metal" (Boone responds: "this is a fair criticism"), and I'm particularly skeptical of Boone's claim that you can guarantee microsecond response times in the face of SMM, but whatever.
> Inputmon does have the enormous, un-auditable dependency of LLVM and Clang
You mean build-time dependency? Not a run-time one.
If that bothers you, there's simpler/smaller compilers out there (TinyCC and the Portable C Compiler come to mind, but there's others). Or drop down to assembly?
> If I start looking into the latest and greatest Qualcomm Nuvia ARM Windows laptops, does it use UEFI?
Yes, those use UEFI.
> Or regular BIOS?
Almost nothing widely produced today uses old "regular BIOS". Even those which seem to use "regular BIOS" are largely UEFI systems acting like a legacy BIOS. Even things like Apple MacBooks which don't use EFI use an Apple custom similar firmware concept far removed from legacy BIOS.
Irc client in uefi: https://github.com/codyd51/uefirc
UEFI library the irc client relies on: https://github.com/rust-osdev/uefi-rs
No more separate GRUB/boot loader code paths needed; boot Linux from UEFI by loading a kernel: https://pretalx.com/devconf-cz-2024/talk/W3AVCT/
Have noodled around with a side-project generating an entire system from boot loader via LLMs but haven't had energy for it given job is the same headspace that needs to be ignored once in a while to not burnout; ultimately want to boot a model of my Linux use (am using bpf to plan and model everything possible and convert it to a compute schedule for sched_ext) and just have a kernel <> model architecture
For security am considering how to embed in the model various authentication obligations to block access to certain blocks of memory without confirmation via webcam and key or something
And on "Be aware of the Windows-ness of EFI" commentary the resemblance to Windows coding style https://computernewb.com/~lily/files/Documents/NTDesignWorkb... is no accident. We leveraged this coding methodology as we evolved the original Intel Boot Initiative then EFI and then UEFI code and specification https://www.intel.com/content/dam/www/public/us/en/documents...
https://app.opencve.io/cve/CVE-2026-97631
To me, UEFI is like "leveraging the waste disposal methodology" of dumping your toxic waste in a lake. Yes, it's more convenient for you, but it does lasting damage and causes years of suffering for millions of people; and eventually somebody else has to clean up your mess, at far greater cost than if you'd just done something sensible to begin with.
I could probably say the same thing about X-Windows.
But, although FAT32 does indeed have the virtue of relative simplicity, that's no excuse for VFAT.
I wonder when Microsoft will stop being a "UTF-16 house" adding UTF-16 to new projects... They did it again to LSP, and that was in 2016. Maybe by 2045 Microsoft will use UTF-8 for new projects, and then by 2100 we can switch to UTF-8 by default.
[0] https://learn.microsoft.com/en-us/gaming/gdk/docs/gdk-dev/ov...
That one is explainable by the fact that it was developed for VS Code, a typescript/javascript project. Javascript uses UTF-16 for strings (for historical reasons unrelated to Microsoft, though they are the same reasons that made MS use UCS-2 during the same time period).
> UTF-16 is used by the Windows API, and by many programming environments such as Java and Qt. The variable-length character of UTF-16, combined with the fact that most characters are not variable-length (so variable length is rarely tested), has led to many bugs in software, including in Windows itself.
I was trying to say: If all the components in your stack are javascript-based, it makes sense that your RPC-API would also use UTF-16. It wasn't Microsoft pushing it for historical Windows reasons as GP implied, it was dictated by a JS stack they chose but didn't create.
You can verify no external symbols remain after linkage with: nm -D --undefined-only. This can be incorporated into a build script to verify the binary is valid.
Once you dig into those there are a bunch of sharp edges, or maybe it's just that that EFI environment is so weird compared to typical Linux system or application development.
Best thing to do with it is treat it as a bootloader and use something else a lot more sane than UEFI.
Dare I live in hope that a newer revision will use 8 bit UTF and better conventions.
It's probably worth pointing out that, unless you're writing a replacement for GRUB, Multiboot2 is a reasonable alternative to building a UEFI PE32+ image, and it permits you to still call UEFI services: https://www.gnu.org/software/grub/manual/multiboot2/multiboo... https://wiki.osdev.org/Multiboot
I was pleased last week that I could elicit enough of a UEFI environment from Opus 5.5 to be able to build an UEFI application without enormous, un-auditable dependencies like gnu-efi. Claude distilled the relevant parts of the UEFI interface into a 289-line header file. The example application just displays the keyboard and mouse events on a UEFI framebuffer using a vendored pixel font, thus the name "inputmon": http://canonical.org/~kragen/sw/inputmon-3.tar.gz
The Makefile includes a "run" target to boot it under QEMU with the OVMF implementation of UEFI.
(One fairly surprising feature of all this is that, not counting the time Claude was waiting for me, it took the model a total of about 7 minutes to write and test this. These 7 minutes were spread over almost 15 hours because I ran out of tokens and spent time thinking. This might be a good example of a case where an LLM is literally a million times more productive than a human programmer: the task is algorithmically trivial, and it doesn't involve difficult engineering tradeoffs, but involves deep knowledge of a pile of obfuscated recondite interfaces that are publicly documented and widely used by published open-source software. It is something I've wanted to do for 7 million minutes.)
I'm hoping I can get an in-browser demo of inputmon working next week, but that's probably going to involve doing some surgery on Bochs in order to get an amd64-compatible virtual machine that doesn't require multithreading the way QEMU does.
Inputmon does have the enormous, un-auditable dependency of LLVM and Clang, but that's a horror I'm already resigned to. But with clang, lld, and make, you can build the image from source, and with QEMU and OVMF you can run it in a virtual machine.
I think it's a little bit debatable to call UEFI "bare metal" (Boone responds: "this is a fair criticism"), and I'm particularly skeptical of Boone's claim that you can guarantee microsecond response times in the face of SMM, but whatever.
You mean build-time dependency? Not a run-time one.
If that bothers you, there's simpler/smaller compilers out there (TinyCC and the Portable C Compiler come to mind, but there's others). Or drop down to assembly?
If I'm not mistaken, the "bare metal" part refers to how directly you can touch it once control passes to your code. So definitely qualifies imho.
Not whether a 'glorified bootloader' burned some CPU cycles before that.
The "bare metal" qualifier goes away if underlying OS prevents your code from touching the hardware directly.
If I start looking into the latest and greatest Qualcomm Nuvia ARM Windows laptops, does it use UEFI? Or regular BIOS?
Yes. It's extremely common.
> If I start looking into the latest and greatest Qualcomm Nuvia ARM Windows laptops, does it use UEFI?
Yes, those use UEFI.
> Or regular BIOS?
Almost nothing widely produced today uses old "regular BIOS". Even those which seem to use "regular BIOS" are largely UEFI systems acting like a legacy BIOS. Even things like Apple MacBooks which don't use EFI use an Apple custom similar firmware concept far removed from legacy BIOS.