kexec

Load a new kernel

$ kexec -l [path/to/kernel] --initrd=[path/to/initrd] --command-line=[arguments]

$ kexec -l [path/to/kernel] --initrd=[path/to/initrd] --reuse-cmdline

$ kexec -e

$ kexec -u

kexec [options]

kexec allows the system to boot directly into a new kernel without going through the BIOS/UEFI and bootloader. This enables faster reboots and is essential for kdump (kernel crash dumping).
The process involves loading a kernel into memory with -l, then executing it with -e. This bypasses hardware initialization, significantly reducing reboot time.

-l, --load KERNEL

Load a new kernel into memory

Execute the currently loaded kernel

Unload the loaded kernel

Specify initramfs/initrd image

Kernel command line arguments

Use current kernel's command line

Load kernel for crash dump (kdump)

Requires CONFIG_KEXEC in the kernel. Some hardware may not work correctly after kexec due to missing initialization. Not all drivers handle kexec transitions properly.

kexec was developed to enable fast reboots and kernel crash dumping. It was merged into the Linux kernel in version 2.6.13 (2005) and has become essential for kdump functionality.

kdump(8), systemctl(1), reboot(8)