comment to this effect and switch the default. My old AT91SAM9G20
now boots, fsck's the SD card and runs w/o an issue for the first
time since a 9.1-ish stable build I did a few years ago.
Problems with unmapped I/O:
o un-page-aligned I/O requests to devices fail (notably fsck
and newfs).
o write-back caching was totally broken. write-through caching
needed to be enabled.
o Even page-aligned I/O requests sometimes failed for reasons
not thoroughly investigated.
Suggested by: ian@
MFC after: 2 days
545ec37cd0