@@ Line 1: / Line 1: @@
 Rocky Linux 9 does not use the /etc/default/grub and /boot/grub2/grub.cfg Files any longer.  Instead the BLS (Boot Loader Specification) 'method' is used.  If one reads the documentation from RedHat, it seems like thing got really messy (and confusing).
+==== Quick D for Cloning, err, "Recreating" a drive from a BackUp (IE, the closest thing to Acronis that Linux seems to have) ====
+* Create a duplicate or functionally similar Partition layout to the original
+** CFDISK and "Logical Volume Commands"
+** Use Blivet from a Rocky 8 Live Boot Device<br />
+==== Rough D ====
+* Start from a 'Clean Slate': <code>wipefs -a /dev/sdX</code> (make dang sure the proper 'sdX' is chosen!)
+* Set the Partition Type (MBR or GPT): <code>cfdisk /dev/sdX</code>, (select DOS or GPT, save it (write) )
+* Create Partitions: cfdisk
+** https://en.wikipedia.org/wiki/Partition_type
+** Linux EXT4: $83 (that's Commodore Speaky for 83h)
+** Linux LVM (and LVM2): $8E
+* LVM Stuff using Commands or BLIVET
+** <code>pvcreate /dev/sdX</code>
+** <code>vgcreate VG.NVMe.ROOT /dev/sdX</code>
+*** <code>vgrename WhatEverOldName WhatEverNewName</code>
+** <code>lvcreate -L 64G -n LV.ROOT VG.NVMe.ROOT</code>
+* BLIVET
 ====BLS (Boot Loader Specification)====
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 Look in /boot/loader/entries and / or use GRUBBY
+...see below for key information on /etc/default/grub and BLS
 ====GRUB "Installation" for MBR / BIOS====
@@ Line 66: / Line 88: @@
 *On '''UEFI systems''', <code>grub2-install</code> registers <code>grubx64.efi</code> with the UEFI boot manager using <code>efibootmgr</code>.
+=== More from ChatGPT on "GRUBing" ===
+= '''Comprehensive Guide to Installing GRUB on Rocky Linux (UEFI & BIOS)''' =
+This guide covers:
+* '''UEFI bootloader installation''' on a target drive.
+* '''Legacy BIOS (MBR) bootloader installation'''.
+* '''BLS (Boot Loader Specification) and its effect on <code>grub2-mkconfig</code>.'''
+* '''GRUB Boot Stages Explanation (Stage 1, Stage 1.5, Stage 2).'''
+* '''How to properly configure bootloader entries and verify installation.'''
+----
+== '''1. Understanding GRUB Boot Stages''' ==
+{| class="wikitable"
+!'''GRUB Stage'''
+!'''Description'''
+!'''Applies To'''
+|-
+|'''Stage 1'''
+|'''MBR code''' (first 512 bytes of disk) loads Stage 1.5 or Stage 2.
+|'''Legacy BIOS (MBR) Only'''
+|-
+|'''Stage 1.5'''
+|Located in the first 30KB after MBR, it helps find <code>/boot/grub2</code>.
+|'''Legacy BIOS (MBR) Only'''
+|-
+|'''Stage 2'''
+|Loads the GRUB menu, kernel, and initrd.
+|'''Both UEFI and BIOS'''
+|-
+|'''UEFI Firmware Boot'''
+|Uses the '''EFI System Partition (ESP)''' instead of MBR. Loads <code>grubx64.efi</code>.
+|'''UEFI Only'''
+|}
+----
+== '''2. Installing GRUB for UEFI Booting''' ==
+=== '''A. Identify the Target Drive''' ===
+List available drives and partitions:
+Look for the '''EFI System Partition (ESP)''', usually '''formatted as FAT32 (<code>vfat</code>)'''.
+Example: If the target drive is <code>/dev/sdb</code>, and the EFI partition is <code>/dev/sdb1</code>, mount it:
+=== '''B. Bind System Directories (for Chroot)''' ===
+If configuring an external system:
+=== '''C. Install Required UEFI GRUB Packages''' ===
+=== '''D. Install GRUB to the Target Drive''' ===
+* <code>--target=x86_64-efi</code> → Specifies '''UEFI mode'''.
+* <code>--efi-directory=/boot/efi</code> → Ensures GRUB is installed in the EFI partition.
+* <code>--bootloader-id=rocky</code> → Labels the boot entry as '''"Rocky"'''.
+* <code>--recheck</code> → Forces a re-scan of the drive layout.
+=== '''E. Generate the GRUB Configuration''' ===
+⚠ '''However, Rocky Linux follows BLS, which makes this step less critical''' (explained in Section 4).
+----
+== '''3. Installing GRUB for Legacy BIOS (MBR Boot)''' ==
+=== '''A. Mount the Target Drive's Root Partition''' ===
+If the system has a separate <code>/boot</code> partition:
+=== '''B. Chroot into the Target System''' ===
+=== '''C. Install Required BIOS GRUB Packages''' ===
+=== '''D. Install GRUB to the MBR of the Target Drive''' ===
+* <code>--target=i386-pc</code> → '''Required for Legacy BIOS (MBR) booting'''.
+* <code>/dev/sdb</code> → '''Must be the whole disk (not a partition like <code>/dev/sdb1</code>)'''.
+* <code>--recheck</code> → Forces a disk layout rescan.
+=== '''E. Generate the GRUB Configuration''' ===
+⚠ '''But due to BLS, <code>grub.cfg</code> is no longer the main configuration source.'''
+----
+== '''4. Understanding BLS (Boot Loader Specification)''' ==
+Rocky Linux follows '''BLS (Boot Loader Specification)''', meaning '''boot entries are controlled by systemd-boot entries, not <code>grub2-mkconfig</code>'''.
+=== '''How to Manually Manage BLS Entries''' ===
+# '''List Existing Boot Entries:'''
+# '''Manually Create a BLS Entry:'''
+# '''Example BLS Entry (<code>rocky.conf</code>)'''
+# '''Enable BLS Support in GRUB (if needed)'''
+=== '''Why BLS Makes <code>grub2-mkconfig</code> Less Relevant''' ===
+* '''Traditional GRUB entries are no longer used''' in Rocky Linux.
+* The '''bootloader reads BLS entries instead'''.
+* '''<code>grub.cfg</code> is still used for bootloader settings''', but '''kernel entries are controlled by BLS'''.
+----
+== '''5. Verify Installation''' ==
+=== '''Check EFI Boot Entries (For UEFI Only)''' ===
+=== '''Check GRUB Installation''' ===
+=== '''Check BLS Entries''' ===
+=== '''Reboot and Test''' ===
+----
+== '''6. Summary''' ==
+{| class="wikitable"
+!'''Boot Mode'''
+!'''Target Option for GRUB'''
+!'''Install Command'''
+!'''Config Location'''
+|-
+|'''UEFI'''
+|<code>x86_64-efi</code>
+|<code>grub2-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=rocky</code>
+|<code>/boot/efi/EFI/rocky/grub.cfg</code>
+|-
+|'''BIOS (MBR)'''
+|<code>i386-pc</code>
+|<code>grub2-install --target=i386-pc /dev/sdb</code>
+|<code>/boot/grub2/grub.cfg</code>
+|-
+|'''BLS (Rocky Linux Default)'''
+|<code>systemd-boot controlled</code>
+|<code>bootctl list</code>
+|<code>/boot/loader/entries/</code>
+|}
 <br />
+== '''1. The Presence (or Absence) of <code>/boot/grub2/grub.cfg</code>''' ==
+* If '''<code>grub.cfg</code> exists''', GRUB will parse it.
+* If '''<code>grub.cfg</code> does NOT exist''', GRUB will attempt to '''read the BLS entries directly''' instead.
+This means:
+✔ '''Deleting <code>grub.cfg</code> forces GRUB to rely entirely on BLS.'''
+✔ '''Regenerating <code>grub.cfg</code> (<code>grub2-mkconfig</code>) puts GRUB back into a "hybrid mode" where it may still reference BLS but also maintain compatibility with legacy boot setups.'''
+----
+== '''2. GRUB’s Bootloader Installation (<code>grub2-install</code>)''' ==
+The actual bootloader installed to the disk controls whether it defaults to '''BLS mode or <code>grub.cfg</code> mode'''.
+When GRUB is installed with:
+(''where <code>/dev/sdX</code> is your boot disk, like <code>/dev/sda</code> or <code>/dev/nvme0n1</code>''), it does the following:
+* Sets up '''GRUB’s core image''' (<code>/boot/grub2/i386-pc/core.img</code> for BIOS systems or <code>/boot/efi/EFI/rocky/grubx64.efi</code> for UEFI systems).
+* Embeds the logic for '''how GRUB will find and load boot entries'''.
+* If BLS is active, it instructs GRUB to '''skip parsing <code>grub.cfg</code> and go directly to BLS entries'''.
+This means: ✔ If GRUB was installed '''with BLS enabled''', even if <code>grub.cfg</code> exists, it may not be used.
+✔ If GRUB was installed '''without BLS support''', it will fall back to <code>grub.cfg</code>.
+----
+== '''How to Explicitly Switch Between BLS and <code>grub.cfg</code>''' ==
+=== '''To Force BLS Mode (and Ignore <code>grub.cfg</code> Completely)''' ===
+# '''Ensure BLS entries exist''':  If this folder is empty, something is broken.
+# '''Delete <code>grub.cfg</code>''' (this ensures GRUB won’t use it):
+# '''Ensure GRUB is installed with BLS support''':  ''(For UEFI systems; adjust for BIOS if needed.)''
+# '''Reboot''' and verify that <code>grub.cfg</code> is no longer in use.
+----
+=== '''To Force Legacy <code>grub.cfg</code> Mode (and Ignore BLS)''' ===
+# '''Ensure <code>grub.cfg</code> is present''':
+# '''Reinstall GRUB to disable BLS mode''':  ''(The <code>--no-bootloader-spec</code> flag explicitly prevents GRUB from using BLS.)''
+# '''Reboot''' and verify that <code>grub.cfg</code> is being used.
+----
+=== '''Final Answer''' ===
+✔ '''The real switch between BLS and <code>grub.cfg</code> is NOT in <code>/etc/default/grub</code>—it's controlled by how GRUB is installed and configured.'''
+✔ '''Deleting <code>grub.cfg</code> forces BLS mode, provided GRUB was installed with BLS support.'''
+✔ '''Reinstalling GRUB with <code>--no-bootloader-spec</code> forces it to use <code>grub.cfg</code> instead of BLS.'''
+✔ '''To change modes, you must either delete <code>grub.cfg</code> (to force BLS) or reinstall GRUB (to force legacy mode).'''

Modern GRUBing: Difference between revisions