Replace GRUB with ZFSBootMenu bootloader

This is a major change that replaces the GRUB bootloader with ZFSBootMenu,
providing native ZFS boot environment support.

Key changes:
- EFI partition reduced from 1GB to 512MB (only holds ZFSBootMenu)
- EFI now mounts at /efi instead of /boot
- Kernel and initramfs live on ZFS root (enables snapshot boot with matching kernel)
- Downloads pre-built ZFSBootMenu EFI binary from get.zfsbootmenu.org
- Creates EFI boot entries for all disks in multi-disk configurations
- Syncs ZFSBootMenu to all EFI partitions for redundancy
- Sets org.zfsbootmenu:commandline on zroot/ROOT for kernel cmdline inheritance
- Sets bootfs pool property for default boot environment
- AMD GPU workarounds (pg_mask, cwsr_enable) added to kernel cmdline when AMD detected

Deleted GRUB snapshot tooling (no longer needed):
- custom/grub-zfs-snap
- custom/40_zfs_snapshots
- custom/zz-grub-zfs-snap.hook
- custom/zfs-snap-prune

Updated helper scripts:
- zfssnapshot: removed grub-zfs-snap call, shows ZFSBootMenu tip
- zfsrollback: removed grub-zfs-snap call, notes auto-detection

Tested configurations:
- Single disk installation
- 2-disk mirror (mirror-0)
- 3-disk RAIDZ1 (raidz1-0)
- All boot correctly with ZFSBootMenu

1 files changed, 0 insertions, 160 deletions

diff --git a/custom/grub-zfs-snap b/custom/grub-zfs-snap
deleted file mode 100644
index 27f2c1f..0000000
--- a/custom/grub-zfs-snap
+++ /dev/null
@@ -1,160 +0,0 @@
-#!/bin/bash
-# grub-zfs-snap - Generate GRUB menu entries for ZFS snapshots
-#
-# This script scans ZFS snapshots and generates GRUB submenu entries
-# allowing boot into previous system states.
-#
-# Usage: grub-zfs-snap [--generate]
-#   --generate    Output GRUB menu entries (called by /etc/grub.d/40_zfs_snapshots)
-#   (no args)     Regenerate GRUB config
-#
-# Installation:
-#   1. Copy this script to /usr/local/bin/grub-zfs-snap
-#   2. Copy 40_zfs_snapshots to /etc/grub.d/
-#   3. Run: grub-mkconfig -o /boot/grub/grub.cfg
-
-set -e
-
-# Configuration
-POOL_NAME="${POOL_NAME:-zroot}"
-ROOT_DATASET="${ROOT_DATASET:-ROOT/default}"
-MAX_SNAPSHOTS="${MAX_SNAPSHOTS:-10}"
-
-# Get full dataset path
-FULL_DATASET="${POOL_NAME}/${ROOT_DATASET}"
-
-# Colors for terminal output
-RED='\033[0;31m'
-GREEN='\033[0;32m'
-NC='\033[0m'
-
-info() { echo -e "${GREEN}[INFO]${NC} $1" >&2; }
-error() { echo -e "${RED}[ERROR]${NC} $1" >&2; exit 1; }
-
-# Check if running as root
-check_root() {
-    if [[ $EUID -ne 0 ]]; then
-        error "This script must be run as root"
-    fi
-}
-
-# Get kernel and initramfs paths
-get_kernel_info() {
-    # Find the LTS kernel
-    KERNEL=$(ls /boot/vmlinuz-linux-lts 2>/dev/null || ls /boot/vmlinuz-linux 2>/dev/null | head -1)
-    INITRD=$(ls /boot/initramfs-linux-lts.img 2>/dev/null || ls /boot/initramfs-linux.img 2>/dev/null | head -1)
-
-    if [[ -z "$KERNEL" ]] || [[ -z "$INITRD" ]]; then
-        error "Could not find kernel or initramfs"
-    fi
-
-    # Get just the filenames
-    KERNEL_FILE=$(basename "$KERNEL")
-    INITRD_FILE=$(basename "$INITRD")
-}
-
-# Get GRUB root device hint
-get_grub_root() {
-    # Get the EFI partition device
-    local efi_dev=$(findmnt -n -o SOURCE /boot 2>/dev/null | head -1)
-    if [[ -z "$efi_dev" ]]; then
-        # Fallback - assume first partition of first disk
-        echo "hd0,gpt1"
-        return
-    fi
-
-    # Convert to GRUB device notation
-    # This is simplified - may need adjustment for complex setups
-    local disk=$(echo "$efi_dev" | sed 's/[0-9]*$//')
-    local part=$(echo "$efi_dev" | grep -o '[0-9]*$')
-
-    # Get disk index (simplified - assumes /dev/sda or /dev/vda style)
-    echo "hd0,gpt${part}"
-}
-
-# Generate GRUB menu entries for snapshots
-generate_entries() {
-    get_kernel_info
-
-    local grub_root=$(get_grub_root)
-    local hostid=$(hostid)
-
-    # Get list of snapshots, sorted by creation time (newest first)
-    local snapshots=$(zfs list -H -t snapshot -o name,creation -s creation -r "$FULL_DATASET" 2>/dev/null | \
-                      grep "^${FULL_DATASET}@" | \
-                      tac | \
-                      head -n "$MAX_SNAPSHOTS")
-
-    if [[ -z "$snapshots" ]]; then
-        return
-    fi
-
-    # Generate submenu
-    cat << 'SUBMENU_START'
-submenu 'ZFS Snapshots' --class zfs {
-SUBMENU_START
-
-    while IFS=$'\t' read -r snapshot creation; do
-        local snap_name="${snapshot##*@}"
-        local snap_date=$(echo "$creation" | awk '{print $1, $2, $3, $4, $5}')
-
-        cat << ENTRY
-    menuentry '${snap_name} (${snap_date})' --class zfs {
-        insmod part_gpt
-        insmod fat
-        insmod zfs
-        search --no-floppy --fs-uuid --set=root $(grub-probe --target=fs_uuid /boot)
-        echo 'Loading Linux kernel...'
-        linux /${KERNEL_FILE} root=ZFS=${snapshot} ro spl.spl_hostid=0x${hostid}
-        echo 'Loading initial ramdisk...'
-        initrd /${INITRD_FILE}
-    }
-ENTRY
-    done <<< "$snapshots"
-
-    echo "}"
-}
-
-# Regenerate GRUB configuration
-regenerate_grub() {
-    check_root
-    info "Regenerating GRUB configuration..."
-    grub-mkconfig -o /boot/grub/grub.cfg
-    info "Done. ZFS snapshots added to GRUB menu."
-}
-
-# List current snapshots
-list_snapshots() {
-    echo "ZFS Snapshots for ${FULL_DATASET}:"
-    echo ""
-    zfs list -H -t snapshot -o name,creation,used -s creation -r "$FULL_DATASET" 2>/dev/null | \
-        grep "^${FULL_DATASET}@" | \
-        tac | \
-        head -n "$MAX_SNAPSHOTS" | \
-        while IFS=$'\t' read -r name creation used; do
-            local snap_name="${name##*@}"
-            printf "  %-30s %s (used: %s)\n" "$snap_name" "$creation" "$used"
-        done
-}
-
-# Main
-case "${1:-}" in
-    --generate)
-        generate_entries
-        ;;
-    --list)
-        list_snapshots
-        ;;
-    "")
-        regenerate_grub
-        ;;
-    *)
-        echo "Usage: $0 [--generate|--list]"
-        echo ""
-        echo "Options:"
-        echo "  --generate    Output GRUB menu entries (for /etc/grub.d/)"
-        echo "  --list        List available snapshots"
-        echo "  (no args)     Regenerate GRUB configuration"
-        exit 1
-        ;;
-esac