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You had me with “avoid C standard library” but lost me at “incoming Linux syscalls directly”. Windows support is a requirement, and no WSL2 doesn’t count. C s

You had me with “avoid C standard library” but lost me at “incoming Linux syscalls directly”. Windows support is a requirement, and no WSL2 doesn’t count. C standard library is pretty bad and it’d be great if not using it was a little easier and more common.

pmc00 1y ago
You can do this in Windows too, useful if you want tiny executables that use minimum resources. I wrote this little systemwide mute utility for Windows that way, annoying to be missing some parts of the CRT but not bad, code here: https://github.com/pablocastro/minimute https://github.com/pablocastro/minimute
- gpm 1y ago
  I thought windows had an unstable syscall interface?
  - LegionMammal978 1y ago
    It looks like that project does link against the usual Windows DLLs, it just doesn't use a static or dynamic C runtime.
    - pmc00 1y ago
      Windows isn’t quite like Linux in that typically apps don’t make syscalls directly. Maybe you could say what’s in ntdll is the system call contract, but in practice you call the subsystem specific API, typically the Win32 API, which is huge compared to the Linux syscall list because it includes all sorts of things like UI, COM (!), etc. The project has some of the properties discussed above such as not having a typical main() (or winmain), because there’s no CRT to call it.
  - Dwedit 1y ago
    Pretty much yeah. You have your usual Win32 API functions found in libraries like Kernel32, User32, and GDI32, but since after Windows XP, those don't actually make system calls. The actual system calls are found in NTDLL and Win32U. Lots of functions you can import, and they're basically one instruction long. Just SYSENTER for the native version, or a switch back to 64-bit mode for a WOW64 DLL. The names of the function always begin with Nt, like NtCreateFile. There's a corresponding Kernel mode call that starts with Zw instead, so in Kernel mode you have ZwCreateFile. But the system call numbers used with SYSENTER are indeed reordered every time there's a major version change to Windows, so you just call into NTDLL or Win32U instead if you want to directly make a system call.
antihero 1y ago
> Windows support is a requirement Why, exactly?
AnimalMuppet 1y ago
> Windows support is a requirement... For what? There is some software for which Windows support is required. There are others for which it is not, and never will be. (And for an article about running ELF files on RiscV with a Linux OS, the "Windows support" complaint seems a bit odd...)
throwawaysoxjje 1y ago
A requirement from whom? To do what?
rfl890 1y ago
You can make CRT-free Win32 programs, read this guide[1] and you're all set. I've written a couple CLI utilities which are completely CRT-free and weigh just under a few kilobytes. [1]: https://nullprogram.com/blog/2023/02/15/ https://nullprogram.com/blog/2023/02/15/
- forrestthewoods 1y ago
  Great post!
- matheusmoreira 1y ago
  Almost freestanding. It still requires you to link against kernel32 and use the functions it provides. This is because issuing system calls directly to the Windows kernel is not supported. The kernel developers reserve the right to change things like system call numbers, so they can't be hardcoded into the application.
  - forrestthewoods 1y ago
    > Almost freestanding. It still requires you to link against kernel32 Nitpick: the phrase “link against kernel32” feels like a Linux-ism. If you’re only calling a few function you need to load kernel32.dll and call some functions in it. But that’s a slightly different operation than linking against it. At least how I’ve always used the term link. You’re not wrong in principle. But Linux and Windows do a lot of things differently wrt linking and loading libs. (I think Windows does it waaay better but ymmv)
    - matheusmoreira 1y ago
      Loading means creating a memory image of the library. Linking means resolving the symbols to addresses within that memory image. Loading a library and calling some functions from it is linking. The function pointer you receive is your link to the library function.
      - forrestthewoods 1y ago
WJW 1y ago
Obviously only a requirement if you intend your software to run under windows. But if you don't, why bother. Not all software is intended to be distributed to users far and wide. Some of it is just for yourself, and some of it will only ever run on linux servers.
- forrestthewoods 1y ago
  > some of it will only ever run on linux servers. I’ve spent quite a lot of time dealing with code that will ever run on Linux which did not in fact only ever run on Linux! Obviously for hobby projects anyone can do what they want. But adult projects should support Windows imho and consider Windows support from the start. Cross-platform is super easy unless you choose to make it hard.
  - deleted 1y ago
    [deleted]
  - WJW 1y ago
    I don't think we are talking about the same type of software? The type I was talking about will only ever run on Linux because it's a (HTTP-ish) server that will only ever run on Linux. Probably a server that is only ever run by a single company on a single CPU type. That company will have complete control of the OS stack, so if it says no Windows, then no Windows has to be supported.
    - forrestthewoods 1y ago
      cool
  - matheusmoreira 1y ago
    > But adult projects should support Windows imho and consider Windows support from the start. Hope whatever "adult" is working on the project this is getting paid handsomely. They'd certainly need to pay me big bucks to care about Windows support. In any case, Linux system call ABI is becoming a lingua franca of systems programming. BSDs have implemented Linux system calls. Windows has straight up included Linux in the system. It looks like simply targeting Linux can easily result in a binary that actually does run anywhere.

pmc00 1y ago

You can do this in Windows too, useful if you want tiny executables that use minimum resources. I wrote this little systemwide mute utility for Windows that way, annoying to be missing some parts of the CRT but not bad, code here: https://github.com/pablocastro/minimute https://github.com/pablocastro/minimute

gpm 1y ago
I thought windows had an unstable syscall interface?
- LegionMammal978 1y ago
  It looks like that project does link against the usual Windows DLLs, it just doesn't use a static or dynamic C runtime.
  - pmc00 1y ago
    Windows isn’t quite like Linux in that typically apps don’t make syscalls directly. Maybe you could say what’s in ntdll is the system call contract, but in practice you call the subsystem specific API, typically the Win32 API, which is huge compared to the Linux syscall list because it includes all sorts of things like UI, COM (!), etc. The project has some of the properties discussed above such as not having a typical main() (or winmain), because there’s no CRT to call it.
- Dwedit 1y ago
  Pretty much yeah. You have your usual Win32 API functions found in libraries like Kernel32, User32, and GDI32, but since after Windows XP, those don't actually make system calls. The actual system calls are found in NTDLL and Win32U. Lots of functions you can import, and they're basically one instruction long. Just SYSENTER for the native version, or a switch back to 64-bit mode for a WOW64 DLL. The names of the function always begin with Nt, like NtCreateFile. There's a corresponding Kernel mode call that starts with Zw instead, so in Kernel mode you have ZwCreateFile. But the system call numbers used with SYSENTER are indeed reordered every time there's a major version change to Windows, so you just call into NTDLL or Win32U instead if you want to directly make a system call.

antihero 1y ago

> Windows support is a requirement Why, exactly?

AnimalMuppet 1y ago

> Windows support is a requirement... For what? There is some software for which Windows support is required. There are others for which it is not, and never will be. (And for an article about running ELF files on RiscV with a Linux OS, the "Windows support" complaint seems a bit odd...)

throwawaysoxjje 1y ago

A requirement from whom? To do what?

rfl890 1y ago

You can make CRT-free Win32 programs, read this guide[1] and you're all set. I've written a couple CLI utilities which are completely CRT-free and weigh just under a few kilobytes. [1]: https://nullprogram.com/blog/2023/02/15/ https://nullprogram.com/blog/2023/02/15/

forrestthewoods 1y ago
Great post!
matheusmoreira 1y ago
Almost freestanding. It still requires you to link against kernel32 and use the functions it provides. This is because issuing system calls directly to the Windows kernel is not supported. The kernel developers reserve the right to change things like system call numbers, so they can't be hardcoded into the application.
- forrestthewoods 1y ago
  > Almost freestanding. It still requires you to link against kernel32 Nitpick: the phrase “link against kernel32” feels like a Linux-ism. If you’re only calling a few function you need to load kernel32.dll and call some functions in it. But that’s a slightly different operation than linking against it. At least how I’ve always used the term link. You’re not wrong in principle. But Linux and Windows do a lot of things differently wrt linking and loading libs. (I think Windows does it waaay better but ymmv)
  - matheusmoreira 1y ago
    Loading means creating a memory image of the library. Linking means resolving the symbols to addresses within that memory image. Loading a library and calling some functions from it is linking. The function pointer you receive is your link to the library function.
    - forrestthewoods 1y ago

WJW 1y ago

Obviously only a requirement if you intend your software to run under windows. But if you don't, why bother. Not all software is intended to be distributed to users far and wide. Some of it is just for yourself, and some of it will only ever run on linux servers.

forrestthewoods 1y ago
> some of it will only ever run on linux servers. I’ve spent quite a lot of time dealing with code that will ever run on Linux which did not in fact only ever run on Linux! Obviously for hobby projects anyone can do what they want. But adult projects should support Windows imho and consider Windows support from the start. Cross-platform is super easy unless you choose to make it hard.
- deleted 1y ago
  [deleted]
- WJW 1y ago
  I don't think we are talking about the same type of software? The type I was talking about will only ever run on Linux because it's a (HTTP-ish) server that will only ever run on Linux. Probably a server that is only ever run by a single company on a single CPU type. That company will have complete control of the OS stack, so if it says no Windows, then no Windows has to be supported.
  - forrestthewoods 1y ago
    cool
- matheusmoreira 1y ago
  > But adult projects should support Windows imho and consider Windows support from the start. Hope whatever "adult" is working on the project this is getting paid handsomely. They'd certainly need to pay me big bucks to care about Windows support. In any case, Linux system call ABI is becoming a lingua franca of systems programming. BSDs have implemented Linux system calls. Windows has straight up included Linux in the system. It looks like simply targeting Linux can easily result in a binary that actually does run anywhere.