/boot directory

/boot folder contains the kernel file (vmlinuz) and initramfs (initrd) files.

During boot, GRUB reads the MBR. It then knows which partition is bootable and what the filesystem type is.

GRUB has minimal built-in filesystem drivers, such as EXT4 and FAT. It uses them to load the config and the kernel image into memory.

After boot, this disk location is mounted and shown as the /boot filesystem. This lets you update these files during an upgrade.

/boot is accessed from both places

GRUB reads it to load the kernel and initramfs into memory at boot. Userspace apps use it to upgrade or change these files.

Contents

It holds the kernel and initramfs files. It also holds GRUB files, which are also read during boot.