Focusing on the VM Context: How the Kernel and Initramfs Are Loaded
==================================================================

Given the observations, we can now focus on the **VM context** and explore how the kernel and initramfs might be loaded in a **paravirtualized KVM environment**. Since GRUB is confirmed to be the bootloader (via the MBR), but the ``grub.cfg`` file does not contain the expected ``linux`` and ``initrd`` parameters, it’s likely that the boot process is being handled in a non-standard way.

Key Observations
--------------------------------------------------

1. **GRUB is the Bootloader**:

   - The MBR contains GRUB, so GRUB is responsible for loading the kernel and initramfs.

2. ``grub.cfg`` **Does Not Contain** ``linux`` **or** ``initrd``:
   - This suggests that GRUB is not using a standard configuration file to load the kernel and initramfs.

3. **Kernel and Initramfs Exist in** ``/boot/``:

   - The kernel (``vmlinuz-<version>``) and initramfs (``initrd.img-<version>``) files exist in ``/boot/`` and match the running kernel version (``uname -r``).

4. **VM is Paravirtualized**:

   - The VM is running under KVM with paravirtualized drivers, which can influence how the boot process works.

Possible Mechanisms for Loading the Kernel and Initramfs
--------------------------------------------------

Given the above observations, here are the most likely mechanisms for how the kernel and initramfs are being loaded:

1. **Embedded Configuration in GRUB**:

   GRUB might be using an **embedded configuration** to load the kernel and initramfs. This means the boot parameters are hardcoded into GRUB’s core image (``core.img``) rather than being read from ``grub.cfg``.

   **How to Check**:
   
   - Inspect the GRUB environment variables:
     .. code-block:: bash

         sudo grub2-editenv list

   - Check if GRUB’s ``core.img`` contains embedded configuration:
     .. code-block:: bash

         strings /boot/grub2/i386-pc/core.img | grep -iE 'linux|initrd'

2. **Direct Kernel Boot (via Hypervisor)**:

   In some paravirtualized environments, the **hypervisor (KVM)** can directly load the kernel and initramfs into memory, bypassing the bootloader. This is often done using the ``-kernel`` and ``-initrd`` options when starting the VM.

   **How to Check**:
   
   - Review the VM’s configuration file (e.g., XML file for ``libvirt`` or command-line options for ``qemu-kvm``).
   - Check the hypervisor logs for evidence of direct kernel boot:
   
     .. code-block:: bash

         sudo journalctl -u libvirtd

3. **Chainloading from Another Bootloader**:

   GRUB might be **chainloading** another bootloader or boot mechanism that handles the loading of the kernel and initramfs.

   **How to Check**:
   
   - Inspect the ``grub.cfg`` file for ``chainloader`` entries:
     .. code-block:: bash

         cat /boot/grub2/grub.cfg | grep chainloader

4. **Custom GRUB Module or Script**:

   GRUB might be using a **custom module or script** to load the kernel and initramfs. This could be part of a specialized VM setup.

   **How to Check**:
   
   - Look for custom GRUB modules in ``/boot/grub2/i386-pc/``:
     .. code-block:: bash

         ls /boot/grub2/i386-pc/
   - Check for custom scripts in ``/etc/grub.d/``:
   
     .. code-block:: bash

         ls /etc/grub.d/

Next Steps
--------------------------------------------------

1. **Check GRUB Environment Variables**:

   .. code-block:: bash

       sudo grub2-editenv list

2. **Inspect GRUB’s** ``core.img``:

   .. code-block:: bash

       strings /boot/grub2/i386-pc/core.img | grep -iE 'linux|initrd'

3. **Review VM Configuration**:

   Check the VM’s configuration file (e.g., ``libvirt`` XML or ``qemu-kvm`` command line) for direct kernel boot options.

4. **Check Hypervisor Logs**:

   .. code-block:: bash

       sudo journalctl -u libvirtd

5. **Verify Chainloading**:

   Check for ``chainloader`` entries in ``grub.cfg`` or other bootloaders in ``/boot/``.

Summary of Likely Mechanisms
--------------------------------------------------

1. **Embedded Configuration in GRUB**:

   - GRUB’s ``core.img`` might contain hardcoded paths to the kernel and initramfs.

2. **Direct Kernel Boot via Hypervisor**:

   - The hypervisor (KVM) might be directly loading the kernel and initramfs.

3. **Chainloading from Another Bootloader**:

   - GRUB might be chainloading another bootloader or mechanism.

4. **Custom GRUB Module or Script**:

   - A custom GRUB module or script might be handling the boot process.