Here’s an explanation of your partition table, with particular attention to the /boot configuration:

Overview of the Disk (/dev/sda)

Your disk has three main partitions:

  1. /dev/sda1 (EFI System Partition):

    • Size: 200 MB
    • Type: EFI System Partition (FAT32)
    • Mount Point: /boot/efi
    • Purpose: Holds the bootloader files required by UEFI firmware. Systemd-boot resides here and loads the kernel and initramfs.

  2. /dev/sda2 (/boot Partition):

    • Size: 1 GB
    • Type: Linux extended boot
    • Mount Point: /boot
    • Purpose: Stores Linux kernel images (vmlinuz-linux), initramfs files, and related boot data. This separation ensures the kernel and initramfs are accessible, even in cases where the root partition is encrypted.

  3. /dev/sda3 (Encrypted Root Partition):

    • Size: 232.6 GB
    • Type: Linux filesystem
    • Purpose: The rest of the disk is encrypted with LUKS (/dev/mapper/luks-*) and is mounted as both /home and /. This is your main storage for the operating system and user data.

  4. zram0 (Compressed Swap in RAM):

    • Size: 8 GB
    • Type: SWAP
    • Purpose: Acts as swap space, implemented using zram (compressed swap in RAM).

Focus on the /boot Configuration

Why Separate /boot and /boot/efi?

  • /boot/efi:
    • This is a small FAT32 partition required by UEFI.
    • It stores the bootloader (e.g., systemd-boot), its configuration files, and the EFI boot entries (/EFI/BOOT/BOOTX64.EFI).
  • /boot:
    • This partition is unencrypted to ensure that the UEFI firmware can access the kernel (vmlinuz-linux) and the initramfs during boot.
    • It contains Linux kernel images, initramfs files, and any additional boot-related data.

Why Is This Setup Common?

  • When using full disk encryption with LUKS:
    • UEFI cannot directly read encrypted partitions.
    • By creating an unencrypted /boot partition, the bootloader can access the kernel and initramfs required to unlock the encrypted root partition.

How the Boot Process Works in Your Setup:

  1. UEFI Firmware:
    • Reads the bootloader (systemd-boot) from the EFI partition (/dev/sda1).
  2. Systemd-Boot:
    • Loads the kernel and initramfs from the /boot partition (/dev/sda2).
  3. Kernel:
    • Uses the initramfs to decrypt /dev/sda3 and mount it as the root filesystem (/).

Partition Size Considerations

  • EFI Partition (/dev/sda1):
    • 200 MB is sufficient for systemd-boot and bootloaders.
  • Boot Partition (/dev/sda2):
    • 1 GB is adequate for multiple kernels and initramfs files. A typical setup may use only a few hundred MB.
  • Root Partition (/dev/sda3):
    • This partition has most of your storage, encrypted for security.