Add config option to support memory allocations in 9-segment.

Internal "low memory" allocations are currently placed in the UMB
region (0xc0000-0xf0000).  However, there have been reports of some
real machines that do not support DMA to this area of memory.  So, add
a compile time config option (off by default) to support placing all
internal low-memory allocations at the end of the 640K real-memory
area (0x90000-0xa0000).

Signed-off-by: Kevin O'Connor <>
7 files changed