Installer uses EFI System Partition on internal eMMC instead of target SSD

When installing AnduinOS on an SSD in a system that already has LibreELEC installed on the internal eMMC, the installer uses the existing EFI System Partition (ESP) on the eMMC instead of the ESP on the target SSD.

This causes the two operating systems to share the same EFI partition, which can lead to broken boot entries and dual-boot issues.

Hardware

• Device: MeLE Quieter 4C
• CPU: Intel N150
• Boot mode: UEFI
• Internal storage: eMMC (LibreELEC)
• Additional storage: SATA SSD (AnduinOS)

Existing system

Before installing AnduinOS:

• Internal eMMC:

  • EFI System Partition
  • LibreELEC

• SSD:

  • Empty

LibreELEC booted correctly from the internal eMMC.

Installation steps

1. Install LibreELEC on the internal eMMC.
2. Install AnduinOS on the SSD.
3. Reboot the system.

Expected behavior

The installer should:

• create or use an EFI System Partition on the target SSD,
• install its bootloader only on the SSD,
• create an EFI boot entry pointing to the SSD.

LibreELEC and AnduinOS should have completely independent EFI partitions.

Actual behavior

The installer detected and mounted the existing EFI partition on the internal eMMC and installed:

EFI/anduinos/

alongside LibreELEC's existing files.

As a result:

• both operating systems shared the same EFI partition,
• boot entries pointed to the wrong device,
• changing boot order in BIOS did not work correctly,
• the system always booted AnduinOS.

The problem disappeared only after:

• reinstalling AnduinOS,
• ensuring it used its own EFI partition on the SSD,
• reinstalling LibreELEC afterwards so that each OS had its own separate EFI partition.

After that, dual boot worked correctly.

Additional observations

I tested the same hardware using Zorin OS instead of AnduinOS.
Zorin OS correctly installed its bootloader on the SSD EFI partition and coexisted with LibreELEC without any issues.
This suggests the problem is specific to the AnduinOS installer (or its EFI partition selection logic), rather than the firmware or LibreELEC.

Start by locating the installer’s EFI partition selection logic and reproduce the installation with LibreELEC on the internal eMMC and an SSD target. Verify that the installer creates or uses the SSD’s EFI partition, installs AnduinOS there, and creates an EFI entry for the SSD without modifying the eMMC partition.