idr gently pointed out today that not only is the sysfs rom file 
interface somewhat unintuitive (despite my efforts and initial 
implementation), but it's also undocumented!  This patch to 
Documentation/filesystems/sysfs-pci.txt corrects the latter problem; the 
former is a userland ABI now though, so we're stuck with it for awhile 
at least.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>