Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

  looking at device '/devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sr0':
    KERNEL=="sr0"
    SUBSYSTEM=="block"
    DRIVER==""
    ATTR{range}=="1"
    ATTR{ext_range}=="1"
    ATTR{removable}=="1"
    ATTR{ro}=="0"
    ATTR{size}=="1270788"
    ATTR{alignment_offset}=="0"
    ATTR{discard_alignment}=="0"
    ATTR{capability}=="19"
    ATTR{stat}=="    1040     1944    12088    36076        0        0        0        0        0    32340    36076"
    ATTR{inflight}=="       0        0"

  looking at parent device '/devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0':
    KERNELS=="1:0:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS=="sr"
    ATTRS{device_blocked}=="0"
    ATTRS{type}=="5"
    ATTRS{scsi_level}=="6"
    ATTRS{vendor}=="HL-DT-ST"
    ATTRS{model}=="DVDRAM GSA-T50L "
    ATTRS{rev}=="SC04"
    ATTRS{state}=="running"
    ATTRS{timeout}=="30"
    ATTRS{iocounterbits}=="32"
    ATTRS{iorequest_cnt}=="0x5d263"
    ATTRS{iodone_cnt}=="0x17af9"
    ATTRS{ioerr_cnt}=="0x0"
    ATTRS{modalias}=="scsi:t-0x05"
    ATTRS{evt_media_change}=="0"
    ATTRS{queue_depth}=="1"
    ATTRS{queue_type}=="none"

  looking at parent device '/devices/pci0000:00/0000:00:1f.2/host1/target1:0:0':
    KERNELS=="target1:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS==""

  looking at parent device '/devices/pci0000:00/0000:00:1f.2/host1':
    KERNELS=="host1"
    SUBSYSTEMS=="scsi"
    DRIVERS==""

  looking at parent device '/devices/pci0000:00/0000:00:1f.2':
    KERNELS=="0000:00:1f.2"
    SUBSYSTEMS=="pci"
    DRIVERS=="ata_piix"
    ATTRS{vendor}=="0x8086"
    ATTRS{device}=="0x2928"
    ATTRS{subsystem_vendor}=="0x103c"
    ATTRS{subsystem_device}=="0x30dd"
    ATTRS{class}=="0x01018a"
    ATTRS{irq}=="21"
    ATTRS{local_cpus}=="00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000003"
    ATTRS{local_cpulist}=="0-1"
    ATTRS{modalias}=="pci:v00008086d00002928sv0000103Csd000030DDbc01sc01i8a"
    ATTRS{numa_node}=="-1"
    ATTRS{dma_mask_bits}=="32"
    ATTRS{consistent_dma_mask_bits}=="32"
    ATTRS{enable}=="1"
    ATTRS{broken_parity_status}=="0"
    ATTRS{msi_bus}==""

  looking at parent device '/devices/pci0000:00':
    KERNELS=="pci0000:00"
    SUBSYSTEMS==""
    DRIVERS==""