If operations using other REX bits (for r8-r15) use capability operands more than 64-bit operands in capability mode, then we could redefine REX.W to indicate capability-wide operations and use 06 for 64-bit operations. Probably worth adding a note about this in the rationale section of the x86 chapter.
If operations using other REX bits (for r8-r15) use capability operands more than 64-bit operands in capability mode, then we could redefine REX.W to indicate capability-wide operations and use 06 for 64-bit operations. Probably worth adding a note about this in the rationale section of the x86 chapter.