Kernelimage

KernelImage is the binary artifact that represents the core of an operating system kernel for a given hardware architecture. It contains the kernel code, static data, and initialization structures required to start the system. The kernel image is produced by the kernel build process and is loaded into memory by a bootloader during system startup. After loading, the kernel image is decompressed if compressed and handed control to the kernel's startup routine.

Formats and variants vary by architecture. In Linux, common formats include vmlinux (uncompressed ELF), zImage and bzImage (compressed images suitable for bootloaders). Compression may use gzip, Bzip2, or LZMA depending on configuration and architecture. Bootloaders such as GRUB, LILO, or U-Boot are responsible for loading the kernel image and passing boot parameters, such as root= and initrd, to the kernel.

Build process and file naming follow the kernel source tree. The image is generated from source with a build system (make); targets include arch/<arch>/boot/bzImage or arch/<arch>/boot/vmlinux, among others. The resulting image is named and placed according to distribution conventions and bootloader expectations.

Booting sequence and role in the system lifecycle. The bootloader loads the kernel image into memory, sets up a minimal environment, and transfers control to the kernel’s entry point. The kernel then decompresses if needed, initializes hardware and subsystems, mounts the root filesystem, and starts user space.

Terminology and usage notes. The term KernelImage may appear in older documentation or boot configurations. In modern practice, terms like kernel binary or kernel image are common, with actual filenames such as vmlinuz or bzImage varying across distributions and setups.