On 2014-11-04, at 19:25, Chuck Arney wrote: > A 64-bit address is only ambiguous when the high word is zero and the high > bit of the low word is on. When the high word is non-zero all 32 bits of the > low word can address storage locations without ambiguity. > I'm not sure why you're even discussing 64 bit addresses when in in AMODE 31. Isn't that a contradiction in terms?
How do VM and Linux, which I understand to not block that range of addresses deal with the problem? Isn't there a bit in the old PSW that distinguishes between AMODE 31 and AMODE 64? Give me more context. Where might I encounter a 64-bit address such as 0000 0000 8000 1000 and be uncertain whether it was to be interpreted in AMODE 31 or AMODE 64? -- gil
