The error you're encountering, Could not access KVM kernel module: No such file or directory, indicates that the KVM (Kernel-based Virtual Machine) module is either not loaded or not available in your kernel. This is a common issue when running QEMU with KVM acceleration on devices where KVM support is not enabled by default, such as most Android-based systems (including LineageOS).

Why This Happens on Fairphone 4 / LineageOS

1. Android Kernel Limitations:

   • Most Android kernels (including LineageOS) do not include KVM support by default, as it is rarely needed on mobile devices.
   • Even if your device's CPU supports virtualization (e.g., ARMv8 with virtualization extensions), the kernel may not expose the /dev/kvm device node.

2. Termux Environment:

   • Termux runs in an unprivileged environment, and even with sudo su, it may not have access to kernel modules or /dev/kvm if the kernel lacks support.

How to Check KVM Availability

Run this command in Termux:

ls /dev/kvm

• If the file does not exist, your kernel does not support KVM.
• If it exists but you still get the error, it may be a permissions issue (unlikely in sudo su).

Possible Solutions

1. Check if Your Kernel Supports KVM

• Run:
  bash

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  cat /proc/cpuinfo | grep -i virtualization

  or:
  bash

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  cat /proc/cpuinfo | grep -i kvm

• If you see no output or KVM is not mentioned, your kernel lacks KVM support.

2. Load KVM Module (If Available)

• Try loading the kvm module manually:
  bash

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  modprobe kvm

• If you get modprobe: not found or Module kvm not found, your kernel does not have KVM compiled.

3. Use a Custom Kernel with KVM Support

• LineageOS does not enable KVM by default, so you would need to:
  1. Build a custom kernel for your Fairphone 4 with CONFIG_KVM enabled.
  2. Flash the custom kernel to your device.
• This is advanced and may void warranties or cause instability.

4. Use QEMU Without KVM (Slower)

• Remove -accel kvm and use TCG (Tiny Code Generator) instead:
  bash

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  qemu-system-aarch64 -machine virt,gic-version=3 -cpu host $LINUX_QEMU_OPTS

• This will be much slower but should work if KVM is unavailable.

5. Use a Different Device/Environment

• If you need KVM acceleration, consider:
  • A Linux PC (native or VM).
  • A rooted Android device with a custom KVM-enabled kernel (rare).
  • Cloud-based ARM VMs (e.g., AWS Graviton, Google Cloud ARM instances).

6. Check for Termux-Specific Workarounds

• Some users have reported success with PRoot or chroot environments in Termux, but KVM will still require kernel support.
• Example:
  bash

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  pkg install proot-distro
  proot-distro install ubuntu
  proot-distro login ubuntu

  Then try running QEMU inside the Ubuntu environment.

Recommendation

Since Fairphone 4's LineageOS kernel likely lacks KVM, your best options are:

1. Use QEMU without KVM (slow but functional).
2. Find a custom kernel for Fairphone 4 with KVM enabled (if available).
3. Use a different device (e.g., a Linux PC or cloud ARM VM) for KVM-accelerated QEMU.