Frequently Asked Question

What is /boot and what's inside it?

/boot contains everything the bootloader needs to start the system: the kernel image (vmlinuz-<version>, a compressed Linux kernel), the initial RAM filesystem (initrd.img or initramfs-<version>.img, a small archive of drivers and scripts), the kernel's configuration (config-<version>), the symbol map for the running kernel (System.map-<version>), and the bootloader's own files, usually under /boot/grub/ for GRUB or /boot/loader/ for systemd-boot. Each installed kernel has its own complete set of these files, which is why /boot accumulates entries when you upgrade.

On a UEFI system there is also /boot/efi, the EFI System Partition, formatted as FAT32 and visible to the firmware. The bootloader binary itself (grubx64.efi, systemd-bootx64.efi) lives there. /boot is usually a small partition (a few hundred megabytes) because the legacy bootloader needs to be able to read it before the main filesystem driver is loaded; that constraint is gradually relaxing as bootloaders gain support for more filesystems.