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Diffstat (limited to 'custom')
| -rw-r--r-- | custom/RESCUE-GUIDE.txt | 218 |
1 files changed, 217 insertions, 1 deletions
diff --git a/custom/RESCUE-GUIDE.txt b/custom/RESCUE-GUIDE.txt index 7c08d78..9587381 100644 --- a/custom/RESCUE-GUIDE.txt +++ b/custom/RESCUE-GUIDE.txt @@ -387,7 +387,223 @@ DATA RECOVERY TIPS 3. BOOT REPAIR ================================================================================ -[To be added] +QUICK REFERENCE +--------------- + tldr grub-install # Install GRUB bootloader + tldr efibootmgr # Manage UEFI boot entries + tldr arch-chroot # Chroot into installed system + man mkinitcpio # Rebuild initramfs + +FIRST: Identify your boot mode +------------------------------ +Check if system is UEFI or Legacy BIOS: + + ls /sys/firmware/efi # If exists, you're in UEFI mode + +If booting from this rescue USB in UEFI mode, you need to fix UEFI. +If booting in Legacy mode, you need to fix MBR/Legacy boot. + + +SCENARIO: Chroot into broken system (preparation for most repairs) +------------------------------------------------------------------ +This is the foundation for most boot repairs. + +1. Find your partitions: + + lsblk -f # Shows filesystems and labels + +2. Mount the root filesystem: + + mount /dev/sdX2 /mnt # Replace with your root partition + + For ZFS root: + + zpool import -R /mnt zroot + zfs mount -a + +3. Mount required system directories: + + mount /dev/sdX1 /mnt/boot # EFI partition (if separate) + mount --bind /dev /mnt/dev + mount --bind /proc /mnt/proc + mount --bind /sys /mnt/sys + mount --bind /sys/firmware/efi/efivars /mnt/sys/firmware/efi/efivars + + Or use arch-chroot (handles mounts automatically): + + arch-chroot /mnt + +4. Now you can run commands as if booted into the system. + + +SCENARIO: Reinstall GRUB (UEFI) +------------------------------- +After chrooting into the system: + + grub-install --target=x86_64-efi --efi-directory=/boot --bootloader-id=GRUB + +If EFI partition is mounted elsewhere: + + grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB + +Regenerate GRUB config: + + grub-mkconfig -o /boot/grub/grub.cfg + + +SCENARIO: Reinstall GRUB (Legacy BIOS/MBR) +------------------------------------------ +After chrooting into the system: + + grub-install --target=i386-pc /dev/sdX # Note: device, not partition + +Regenerate GRUB config: + + grub-mkconfig -o /boot/grub/grub.cfg + + +SCENARIO: Fix UEFI boot entries +------------------------------- +List current boot entries: + + efibootmgr -v + +Delete a broken entry (replace XXXX with boot number): + + efibootmgr -b XXXX -B + +Create a new boot entry: + + efibootmgr --create --disk /dev/sdX --part 1 --label "Arch Linux" \ + --loader /EFI/GRUB/grubx64.efi + +Change boot order (comma-separated boot numbers): + + efibootmgr -o 0001,0002,0003 + +Set next boot only: + + efibootmgr -n 0001 + + +SCENARIO: Rebuild initramfs (kernel panic, missing modules) +----------------------------------------------------------- +After chrooting into the system: + +List available presets: + + ls /etc/mkinitcpio.d/ + +Rebuild for specific kernel: + + mkinitcpio -p linux # Standard kernel + mkinitcpio -p linux-lts # LTS kernel + +Rebuild all: + + mkinitcpio -P + +Check mkinitcpio.conf for ZFS: + + grep "^HOOKS" /etc/mkinitcpio.conf + +For ZFS, HOOKS should include 'zfs': + HOOKS=(base udev autodetect modconf block zfs filesystems keyboard fsck) + + +SCENARIO: GRUB not detecting Windows (dual-boot) +------------------------------------------------ +After chrooting into the system: + +Enable os-prober in GRUB config: + + echo 'GRUB_DISABLE_OS_PROBER=false' >> /etc/default/grub + +Mount the Windows EFI partition if not already mounted. + +Regenerate GRUB config: + + grub-mkconfig -o /boot/grub/grub.cfg + +os-prober should find Windows and add it to the menu. + + +SCENARIO: Restore Windows MBR (remove GRUB, restore Windows boot) +----------------------------------------------------------------- +If you need to remove Linux and restore Windows-only MBR: + + ms-sys -w /dev/sdX # Write Windows 7+ MBR + +Other options: + ms-sys -7 /dev/sdX # Windows 7 MBR specifically + ms-sys -i /dev/sdX # Show current MBR type + + +SCENARIO: Install syslinux (lightweight alternative to GRUB) +------------------------------------------------------------ +For Legacy BIOS: + + syslinux-install_update -i -a -m + +For UEFI, copy the EFI binary: + + cp /usr/lib/syslinux/efi64/* /boot/EFI/syslinux/ + +Create /boot/syslinux/syslinux.cfg with boot entries. + + +SCENARIO: Can't boot - kernel panic with ZFS +-------------------------------------------- +Common causes: +1. ZFS module not in initramfs - rebuild with mkinitcpio +2. Pool name changed - check zpool.cache +3. hostid mismatch - regenerate hostid + +After chrooting: + +Check if ZFS hook is present: + + grep zfs /etc/mkinitcpio.conf + +Regenerate hostid if needed: + + zgenhostid $(hostid) + +Rebuild initramfs: + + mkinitcpio -P + + +SCENARIO: Emergency boot from GRUB command line +----------------------------------------------- +If GRUB loads but config is broken, press 'c' for command line: + +For Linux (non-ZFS): + + set root=(hd0,gpt2) + linux /boot/vmlinuz-linux root=/dev/sda2 + initrd /boot/initramfs-linux.img + boot + +For Linux with ZFS root: + + set root=(hd0,gpt1) + linux /vmlinuz-linux-lts root=ZFS=zroot/ROOT/default + initrd /initramfs-linux-lts.img + boot + +Tab completion works in GRUB command line! + + +BOOT REPAIR TIPS +---------------- +1. Always backup your current EFI partition before making changes +2. Use 'efibootmgr -v' to see full paths and verify entries +3. Some UEFI firmwares are picky about the bootloader path - + try /EFI/BOOT/BOOTX64.EFI as a fallback +4. If all else fails, most UEFI has a boot menu (F12, F8, Esc at POST) +5. GRUB reinstall usually fixes most boot issues +6. For ZFS, the initramfs must include the zfs hook ================================================================================ 4. WINDOWS RECOVERY |