[API Proposal]: Add OperatingSystem.IsLinuxKernelVersionAtLeast

[Neme12]

Background and motivation

Sometimes, I need to know whether I'm on a Linux kernel with at least a specified version to know whether a certain syscall is available and I can do the PInvoke.

API Proposal

namespace System;

public sealed partial class OperatingSystem
{
    public static bool IsLinuxKernelVersionAtLeast(int major, int minor = 0, int build = 0, int revision = 0);

    // Or alternatively, since Linux is a kernel, not an OS
    public static bool HasLinuxKernelVersionAtLeast(int major, int minor = 0, int build = 0, int revision = 0)
}

API Usage

if (OperatingSystem.IsLinuxKernelVersionAtLeast(6, 1)
    // use PInvoke introduced only in linux kernel 6.1

Alternative Designs

No response

Risks

No response

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[vcsjones]

I'd like to better understand some of the scenarios here. The Linux kernel is usually only one part of equation here, there is also the glibc or musl version, and they don't have a strict 1:1 mapping. The libc is more often than not what people are p/invoking to interact with the Linux kernel.

Older libc can run on newer kernels and will simply lack exports to new kernel functionality; or newer libc can run on older kernels and return ENOSYS if the kernel is not capable of fulfilling the request.

[Neme12]

I see, I didn't think of that. My scenario that the kernel only supports the NameToHandleAtFlags.AT_EMPTY_PATH flag in name_to_handle_at from a certain version.

[MichalPetryka]

The Linux kernel is usually only one part of equation here, there is also the glibc or musl version, and they don't have a strict 1:1 mapping. The libc is more often than not what people are p/invoking to interact with the Linux kernel.

Also, would this return true on Android?

[Neme12]

The Linux kernel is usually only one part of equation here, there is also the glibc or musl version, and they don't have a strict 1:1 mapping. The libc is more often than not what people are p/invoking to interact with the Linux kernel.

Also, would this return true on Android?

Yes. Just like IsLinux (I assume) does.

[jkotas]

whether a certain syscall is available

If you can write the glue for syscalls, you should be able to write the glue for version check too.

The version check is often not the best answer. Kernel vendors backport high value features, so the syscall may be available even on lower kernel version. On the other hand, locked down systems can have syscalls blocked even on higher kernel versions.

runtime/src/native/minipal/random.c

Line 126 in e885bb9

if (errno == ENOSYS || errno == EPERM)

is a good example how to do light up well.