x86: Prune redundant x64 from RMPREAD
Patch removes redundant 'x64' attribute from RMPREAD instruction.
Jan Beulich proposes a patch to remove the redundant ‘x64’ attribute from the RMPREAD instruction in the opcodes table. This attribute was found to be unnecessary because RMPREAD already depends on Cpu64, and removing it aligns with the attributes of RMPQUERY. The patch also adds the operand-less form of the instruction.
- proposer
Submitted a patch to remove the redundant 'x64' attribute from the RMPREAD instruction and add its operand-less form.
“As noticed during review of the RMPOPT/RMPDIRTY patch: CpuRMPREAD depends on Cpu64, so the attribute is redundant to specify. This then also matches in particular RMPQUERY. While there also add the missing operand-less form of the insn.”
In Details
This patch modifies opcodes/i386-opc.tbl to remove the x64 flag from the RMPREAD instruction entry. The x64 flag is redundant because RMPREAD already implies 64-bit operation through its dependency on Cpu64. The change also introduces a new entry for the operand-less form of RMPREAD, which was previously missing.
- RMPREAD
- A specific x86 instruction, likely related to memory protection or management, possibly for reading a Read-Modify-Protect (RMP) table entry.
- x64
- Refers to the 64-bit instruction set architecture extensions for x86 processors.
- Cpu64
- An attribute or flag indicating that an instruction is valid or intended for use in 64-bit mode.
- Operand-less form
- An instruction that can be executed without any explicit operands, relying on implicit register operands or default behavior.
- i386-opc.tbl
- A table file used by Binutils to define the opcodes and their properties for the i386 (x86) architecture.