def activate_backup_image(reset=False):
    '''
    Activates the firmware backup image.

    CLI Example:

    Args:
        reset(bool): Reset the CIMC device on activate.

    .. code-block:: bash

        salt '*' cimc.activate_backup_image
        salt '*' cimc.activate_backup_image reset=True

    '''

    dn = "sys/rack-unit-1/mgmt/fw-boot-def/bootunit-combined"

    r = "no"

    if reset is True:
        r = "yes"

    inconfig = """<firmwareBootUnit dn='sys/rack-unit-1/mgmt/fw-boot-def/bootunit-combined'
    adminState='trigger' image='backup' resetOnActivate='{0}' />""".format(r)

    ret = __proxy__['cimc.set_config_modify'](dn, inconfig, False)

    return ret