situation is a high priority which in turn by necessity puts pressure
on the 32-bit Major Opcode space.
-SVP64 itself is already under pressure, being only 24 bits. If it is
-not permitted to take up 25% of EXT001 then it would have to be proposed
-in its own Major Opcode, which on first consideration would be beneficial
-for SVP64 due to the availability of 2 extra bits.
-However when combined with the bitmanip scalar instructions
-requiring two Major opcodes this would come to a grand total of 3 precious
-Major opcodes. On balance, then, sacrificing 25% of EXT001 is the "least
-difficult" choice.
-Alternative locations for SVP64
-Prefixing include EXT006 and EXT017, with EXT006 being most favourable
-as there is room for future expansion.
-
Note also that EXT022, the Official Architectural Sandbox area
available for "Custom non-approved purposes" according to the Power
ISA Spec,