The Linux kernel developers, in their mysterious and infinite wisdom, decided that between version 2.6.17 and 2.6.19 they would change the naming scheme for accessing Flash chips. I am sure the change is documented in a footnote somewhere, but it is not terribly obvious. It is obvious that things that formerly worked are now broken, though. It took me 2 to 3 hours of debugging to track down the fact that:
physmap_flash
…should now be called:
physmap-flash
Once a kernel parameter was changed slightly, everything magically started working again. Why the change? Who knows!? Would you have noticed the difference if you were not looking for it? I didn’t see it for a very long time, personally.