grub.cfg

serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
set timeout=3
set timeout_style=menu

# Load GRUB environment variables
load_env -f /EFI/BOOT/grub.env

# Reset or decrement boot counter based on 'ustate'
if [ "${ustate}" != "1" ]; then
    set boot_counter=3
else
    if [ -z "${boot_counter}" ]; then
        set boot_counter=2
    else
        if [ "${boot_counter}" == "1" ]; then
            set boot_counter=0
        elif [ "${boot_counter}" == "2" ]; then
            set boot_counter=1
        elif [ "${boot_counter}" == "3" ]; then
            set boot_counter=2
        fi
    fi
fi

# Check if boot counter is '0' which means fallback is needed
if [ "${boot_counter}" == "0" ]; then
    set ustate=3
    # Swap the 'rootfs' variable to the other partition, simulating a fallback
    if [ "${rootfs}" == "A" ]; then
        set rootfs="B"
        set rootfs_status_A="Fail"
        set rootfs_status_B="Fallback"
    else
        set rootfs="A"
        set rootfs_status_A="Fallback"
        set rootfs_status_B="Fail"
    fi
    set boot_counter=3 # reset boot counter after fallback
else
    # Determine the default boot entry and set status messages based on 'rootfs'
    if [ "${rootfs}" == "A" ]; then
        set default=0
        set rootfs_status_A="Default"
        set rootfs_status_B="Inactive"
    elif [ "${rootfs}" == "B" ]; then
        set default=1
        set rootfs_status_A="Inactive"
        set rootfs_status_B="Default"
    fi

    # Adjust status based on boot attempt
    if [ "${ustate}" == "1" ]; then
        if [ "${rootfs}" == "A" ]; then
            set rootfs_status_A="Attempt ${boot_counter}"
        else
            set rootfs_status_B="Attempt ${boot_counter}"
        fi
    fi
fi

if [ -z "${device_a}" ]; then
    ## we loose labels when updating, make sure we remember them
    ## remove this when grub search supports partlabel
    ## disadvantage is that you cannot boot the disk anymore when you change it to another pc
    search --no-floppy --label rootfsA --set=device_a
fi

if [ -z "${device_b}" ]; then
    search --no-floppy --label rootfsB --set=device_b
fi


# Save all changes to necessary environment variables at once
save_env -f /EFI/BOOT/grub.env ustate boot_counter rootfs device_a device_b


menuentry "A - ${rootfs_status_A}" {
    #search --no-floppy --label rootfsA --set=root
    set root="${device_a}"
    linux /boot/bzImage root=PARTLABEL=rootfsA rootwait rw oprofile.timer=1 rootfstype=ext4 console=tty console=ttyS0 
}

menuentry "B - ${rootfs_status_B}" {
    #search --no-floppy --label rootfsB --set=root
    set root="${device_b}"
    linux /boot/bzImage root=PARTLABEL=rootfsB rootwait rw oprofile.timer=1 rootfstype=ext4 console=tty console=ttyS0 
}

menuentry "A with kernel from boot partition" {
    linux /bzImage root=PARTLABEL=rootfsA rootwait rw oprofile.timer=1 rootfstype=ext4 console=tty console=ttyS0 
}