How Linux kernel image is loaded at install time despite of no actual bootloader(GRUB) present on hard drive?
Before we move further let's understand how Linux boots up in brief: As soon as power button pressed, motherboard gets the power through SMPS(Switch Mode Power Supply). SMPS converts from AC to DC voltages which motherboard requires. Once motherboard is up, processor gets the power and it start execution from fixed address in EEPROM/Flash drive. This address typically contains a single jump instruction with actual BIOS(Basic Input Output System) firmware code in EEPROM/Flash drive so control goes to BIOS now BIOS performs the POST(Power On Self Test) which means it checks whether basic hardware devices like Hard drive, Display, Keyboard, Mouse etc. are working fine or not Once the POST is finished, BIOS finds the bootable partition on hard drive and hands over the system control to bootloader(GRUB mostly) present in boot partition of hard disk Bootloader loads the kernel and initrd(Iniital RAM Disk). Initrd is minimal file system required to load root file system Kern