msrr

Move Two Registers to System Register (128-bit)

MSRR <sysreg>, <Xt>, <Xt+1>

Writes two general-purpose registers into a 128-bit system register.

Details

Writes two consecutive 64-bit general-purpose registers (Xt and Xt+1) into a 128-bit system register. This is an AArch64-only instruction requiring FEAT_SYSREG128 and may require elevated privilege depending on the system register being accessed. No condition flags are affected.

Pseudocode Operation

SYSREG[sysreg][63:0] ← Xt
SYSREG[sysreg][127:64] ← Xt+1

Example

MSRR sysreg, x3, Xt+1

Encoding

Binary Layout
1101010101
0
1
o0
op1
CRn
CRm
op2
Rt
 
Format System
Opcode 0xD5500000
Extension FEAT_SYSREG128

Operands

  • sysreg
    Reg
  • Xt
    Lo
  • Xt+1
    Hi

Reference (Arm A64 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0xD5500000 MSRR (<systemreg>|S<op0>_<op1>_<Cn>_<Cm>_<op2>), <Xt>, <Xt+1> A64 1101010101 | 0 | 1 | o0 | op1 | CRn | CRm | op2 | Rt

Description

Move two adjacent general-purpose registers to System Register allows the PE to write an AArch64 128-bit System register from two adjacent 64-bit general-purpose registers.

Operation

AArch64.SysRegWrite128(sys_op0, sys_op1, sys_crn, sys_crm, sys_op2, t, t2);