On 9/4/2020 10:46 AM, Seymour J Metz wrote:
VM uses a token of 8X'FF' at the end of the (R1) parameter list. I don't recall what the convention is for the (R0) extended parameter list introduced by VM/SP.
We've adopted "eight bytes of foxes" as an end marker for variable-length parameter lists that use 64-bit pointers. Of course, we realize it means we have a permanent restriction that the singular byte address of "sixteen exabytes minus one" cannot be passed unambiguously as a parameter in such parameter lists. We really don't see that as posing any practical problem for our software even if that byte is available for acquisition.
We're also sort of assuming RSM will never hand out the last 1M or perhaps even 2G virtual in a manner similar to what's done today for the 4K page at x'7FFFF000'.
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