DMB Data memory barrier This instruction is a memory barrier that ensures the ordering of observations of memory accesses, see Data Memory Barrier. 1 1 0 1 0 1 0 1 0 0 0 0 0 0 1 1 0 0 1 1 1 0 1 1 1 1 1 1 DMB (<option>|#<imm>) var types : MBReqTypes; case CRm[1:0] of when '00' => types = MBReqTypes_All; when '01' => types = MBReqTypes_Reads; when '10' => types = MBReqTypes_Writes; when '11' => types = MBReqTypes_All; end; <option> Specifies the limitation on the Memory Effects ordered by the barrier operation, and is encoded in "CRm". For more information on whether a Memory Effect is before or after a barrier instruction, see Data Memory Barrier (DMB). CRm <option> Description xx00 RESERVED 0001 OSHLD This option has the same behavior as LD and is deprecated. 0010 OSHST This option has the same behavior as ST and is deprecated. 0011 OSH This option has the same behavior as SY and is deprecated. 0101 NSHLD This option has the same behavior as LD and is deprecated. 0110 NSHST This option has the same behavior as ST and is deprecated. 0111 NSH This option has the same behavior as SY and is deprecated. 1001 ISHLD This option has the same behavior as LD and is deprecated. 1010 ISHST This option has the same behavior as ST and is deprecated. 1011 ISH This option has the same behavior as SY and is deprecated. 1101 LD Reads are the required access type before the barrier instruction. Reads and writes are the required access types after the barrier instruction. 1110 ST Writes are the required access type, both before and after the barrier instruction. 1111 SY Reads and writes are the required access types, both before and after the barrier instruction. All encodings of "CRm" that are listed as reserved can be encoded using the #<imm> syntax. All reserved options have the same behavior as SY, but software must not rely on this behavior. <imm> Is a 4-bit unsigned immediate, in the range 0 to 15, encoded in the "CRm" field. DataMemoryBarrier(types); 2026-03-26 20:27:25 2026-03_rel