Wayne Topa wrote: > How does the system boot up if /boot is not mounted?
You don't need /boot mounted in order to boot. It only needs to be mounted in order to be updated. Booting happens before the operating system is loaded and so those files are not needed at operating system time. By the time the operating system is running there is no longer any need to access those files. The classic system uses the BIOS to load the MBR (main boot record). (I say classic system uses the BIOS because with very large drives and secure booting the world is changing there.) Assuming GRUB for the boot loader then GRUB will install itself into the MBR. The BIOS loads the MBR and jumps into it which jumps into GRUB. Grub reads the kernel and initrd file from /boot itself. Since this is before the Linux kernel starts it isn't mounted in that system. GRUB loads /boot itself into its own memory which is completely separate from the later Linux booted memory. The /boot/initrd.img image is a small ram disk image. It contains the drivers needed for the kernel to boot the rest of the system. It starts up init as process 1 and then proceeds with the boot. Because GRUB loaded the /boot/initrd.img and /boot/vmlinuz itself those files were not needed to be mounted and available later. Bob
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