I've seen a program which instructs the Athlon XP (32 bits) to remap memory accesses for the purpose of 'creating' UMBs (upper memory blocks) for DOS use. Since this works in real mode, it is evidently a capability independent of the usual paging apparatus of X86 processors. The program usage docs state it is done using specific facilities available in the AMD Athlon XP proc.
Assuming this is done using specific MSRs, but could not find the appropriate processor documentation. Can someone kindly point me in the right direction ?