Most books and courses introduce Linux through shell commands, leaving the kernel as a mysterious black box doing magic behind the scenes. In this post, we will run some experiments to demystify it: the Linux kernel is just a binary that you can build and run.
  • Anna@lemmy.ml
    0·
    1 day ago

    Yeah it’s just as simple as the calculator program I copy pasted in highschool computer class.

  • LeFantome@programming.dev
    0·
    2 days ago

    Well, the kernel is not “just a program” in that it is not like the other programs on your system. If it was, you would “just” run it in your shell. The kernel cannot run this way of course because it is not a user mode program.

    That said, if course the kernel is a program in the sense that it is a set of machine instructions that make the hardware do what you want.

    And the kernel is designed to talk to hardware and other programs—to be the bridge between the two. It is not something an end-user interacts with directly.

    • GlowHuddy@lemmy.world
      0·
      2 days ago

      Well, the kernel is not “just a program” in that it is not like the other programs on your system. If it was, you would “just” run it in your shell. The kernel cannot run this way of course because it is not a user mode program.

      Actually…

      • LeFantome@programming.dev
        0·
        1 day ago

        Point taken but….

        UML requires:

        1 - extensive support from the host kernel above and beyond what is required to execute for regular programs

        2 - the guest kernel to be specially compiled to be a UML guest

        In other words, even though UML allows a guest Linux kernel to execute as a process on a host Linux kernel, that Linux kernel is not “just a program” like every other user mode application is.

  • lemmyseizethemeans@lemmygrad.ml
    0·
    3 days ago

    Thanks op this is a great article. Having compiled kernels since 2.4 or thenabouts, it’s a great topic and I never really thought of it as just another program. Neat stuff!

  • dubyakay@lemmy.ca
    0·
    3 days ago

    On my arch install, all I have is vmlinuz-linux under /boot. How come there’s no further information appended like in the article?

    • ReversalHatchery@beehaw.org
      0·
      9 hours ago

      an arch user doesn’t know that!!

      so, that further information is the kernel’s version number. it helps to keep some older versions. but you didn’t set it up to include the version in the filename.

      és egyébként bojler eladó. processzorra cserélném.

    • atzanteol@sh.itjust.worksEnglish
      0·
      3 days ago

      Different distros vary a bit here, and it will differ if you’re on a system using efi.

      Sometimes /boot isn’t mounted by default (it’s not needed unless you’re updating a kernel). You may be seeing a symlink or placeholder there.

      If you’re using efi there will probably be /boot/EFI or something where your kernel is stored.

      • flying_sheep@lemmy.ml
        0·
        23 hours ago

        The reason there’s no version in the filename is simply that Arch just doesn’t keep old kernels around.

        The vmlinuz-linux just gets replaced whenever you update the linux package and the old one is deleted immediately.

        • atzanteol@sh.itjust.worksEnglish
          0·
          16 hours ago

          That’s… Insanity. Keeping at least one old kernel is amazingly useful if you run into issues with an update.

          • flying_sheep@lemmy.ml
            0·
            9 hours ago

            I agree that it’s be useful, and I think you can just install e.g. the LTS kernel next to the regular one.

            But even without , the arch way isn’t insane either: when something kernel-related breaks, boot with a live system on USB and fix it.

            Case in point: I dimensioned the EFI partition too small, so at some point, me using the zen kernel (which comes with a backup kernel image) messed things up and I couldn’t boot a half-written kernel.

            then I

            1. created and booted a live USB stick,
            2. Mounted my / and /boot partitions manually into /mnt/root/ and /mnt/root/boot
            3. Bind-mounted the live system’s /dev and /proc into /mnt/root/{dev,proc}
            4. chrooted into /mnt/root (resulting in an environment using /dev and /proc from the live system and the rest from my system),
            5. Used regular package manager commands to uninstall the zen kernel and install the regular one, and finally
            6. rebooted into the now working system.

            It’s not crazy, it doesn’t take long, you just need to know how the system works. Upside is that nothing ever breaks permanently, everything is fixable (except hardware failure)

  • davel@lemmy.mlEnglish
    0·
    3 days ago

    It’s a program certainly, but “just a program” is a bit misleading because it places it on the same footing as Doom or cat or an Arduino project. Linux is a ring 0 program, which processors give unique treatment.

    • arthropod_shift@programming.dev
      0·
      13 hours ago

      Reminds me of not long after I started using Linux. I thought the kernel was “just a program” like cat and tried to run the kernel from the terminal, only to be disappointed when a new kernel in fact did not start running inside the terminal window.