K 10
svn:author
V 8
jhibbits
K 8
svn:date
V 27
2020-04-11T00:17:55.854548Z
K 7
svn:log
V 784
powerpc/booke: Use power-of-two mappings in 64-bit pmap_mapdev

Summary:
This reduces the precious TLB1 entry consumption (64 possible in
existing 64-bit cores), by adjusting the size and alignment of a device
mapping to a power of 2, to encompass the full mapping and its
surroundings.

One caveat with this: If a mapping really is smaller than a power of 2,
it's possible to get a machine check or hang if the 'missing' physical
space is accessed.  In practice this should not be an issue for users,
as devices overwhelmingly have physical spaces on power-of-two sizes and
alignments, and any design that includes devices which don't follow this
can be addressed by undefining the POW2_MAPPINGS guard.

Reviewed by:	bdragon
Differential Revision: https://reviews.freebsd.org/D24248

END