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Master the fundamental concepts of the boot process — theory through this focused micro-challenge.
An initramfs is a cpio archive the bootloader loads into memory before the kernel starts. Early kernel code mounts it as a tmpfs root so drivers and scripts can run before the real root disk is available. For example, a typical Linux image ships initramfs-linux.img containing module-loading helpers and init glue that finds the LUKS or LVM root.
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The kernel mounts tmpfs, extracts the cpio archive into rootfs, and executes /init. Dracut-generated images include udev rules to modprobe storage drivers before pivot_root. If /init exits, the kernel panics; keep the process alive until switch_root completes. Inspect an image with lsinitrd or zcat initramfs.img | cpio -itv to see which helpers your distro ships.
You will trace how the bootloader passes an initramfs blob to the kernel and what early /init must accomplish. This exercise requires describing why root-on-LUKS or NFS roots depend on initramfs content before pivot_root.
Simulate initramfs operations in C.
Requirements:
Test:
Three hints are available for this task, revealed one at a time inside the code workspace so you can struggle productively before seeing them.
All starter code and reference implementations are available for your local setup.
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