Bitfields for Intel 82439TX/82443BX Extended SMRAM Control register:
Bit(s)	Description	)
 7	SMRAM location
	=0 compatible SMRAM space at segment A000h
	=1 high SMRAM space at addreses 100A0000h to 100FFFFFh (accessing
	  physical DRAM addresses A0000h to FFFFFh)
 6	(write-clear) access to extended SMRAM memory range when SMRAM space
	  is not open and not in SMM
 5	enable write-through caching of SMRAM
	(forced to 1 by 82443BX, to 0 by 82439TX)
 4	enable L1 caching of SMRAM (forced to 1 by 82443BX)
 3	enable L2 caching of SMRAM (forced to 1 by 82443BX)
 2-1	TSEG size (read-only once SMRAM locked) (see #01123)
	00 128K
	01 256K
	10 512K
	11 1M
 0	enable TSEG (read-only once SMRAM locked) (see #01123)
	when both SMRAM and TSEG are enabled, the top N kilobytes of physical
	  DRAM are no longer claimed by the memory controller, and instead
	  appear as extended SMRAM at an address 256M higher than the physical
	  address
SeeAlso: #01142,#01123,#01099