Issue

• setpci aborts with the following error message, but the message is quite improper.

  # setpci -s 00:00.0 00
  setpci: Missing width.
  Try `setpci --help' for more information.
  

• As you see, setpci says the "width" of the specified device doesn't know. According to setpci's man page, the "width" can be specified by .B, .W, or .L suffix. Here is a part of the man page.

  Each of the previous formats can be followed by +offset to add an
  offset (a hex number) to the address. This feature can be useful for
  addressing of registers living within a capability, or to modify parts
  of standard registers.
  Finally, you should append a width specifier .B, .W, or .L to choose
  how many bytes (1, 2, or 4) should be transferred. The width can be
  omit- ted if you are accessing a named register whose width is well
  known.
  

• As you see, the above description says any of those suffixes should be specified for "+offset", but doesn't have to be specified for either "domain" or "name". However, the current setpci requires a suffix whenever it is run.