DMB

Data Memory Barrier is a memory barrier that ensures the ordering of observations of memory accesses, see Data Memory Barrier.

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11010101000000110011CRm10111111
opcRt

DMB (<option>|#<imm>)

MBReqDomain domain; MBReqTypes types; case CRm<3:2> of when '00' domain = MBReqDomain_OuterShareable; when '01' domain = MBReqDomain_Nonshareable; when '10' domain = MBReqDomain_InnerShareable; when '11' domain = MBReqDomain_FullSystem; case CRm<1:0> of when '00' types = MBReqTypes_All; domain = MBReqDomain_FullSystem; when '01' types = MBReqTypes_Reads; when '10' types = MBReqTypes_Writes; when '11' types = MBReqTypes_All;

Assembler Symbols

<option>

Specifies the limitation on the barrier operation. Values are:

SY
Full system is the required shareability domain, reads and writes are the required access types, both before and after the barrier instruction. This option is referred to as the full system barrier. Encoded as CRm = 0b1111.
ST
Full system is the required shareability domain, writes are the required access type, both before and after the barrier instruction. Encoded as CRm = 0b1110.
LD
Full system is the required shareability domain, reads are the required access type before the barrier instruction, and reads and writes are the required access types after the barrier instruction. Encoded as CRm = 0b1101.
ISH
Inner Shareable is the required shareability domain, reads and writes are the required access types, both before and after the barrier instruction. Encoded as CRm = 0b1011.
ISHST
Inner Shareable is the required shareability domain, writes are the required access type, both before and after the barrier instruction. Encoded as CRm = 0b1010.
ISHLD
Inner Shareable is the required shareability domain, reads are the required access type before the barrier instruction, and reads and writes are the required access types after the barrier instruction. Encoded as CRm = 0b1001.
NSH
Non-shareable is the required shareability domain, reads and writes are the required access, both before and after the barrier instruction. Encoded as CRm = 0b0111.
NSHST
Non-shareable is the required shareability domain, writes are the required access type, both before and after the barrier instruction. Encoded as CRm = 0b0110.
NSHLD
Non-shareable is the required shareability domain, reads are the required access type before the barrier instruction, and reads and writes are the required access types after the barrier instruction. Encoded as CRm = 0b0101.
OSH
Outer Shareable is the required shareability domain, reads and writes are the required access types, both before and after the barrier instruction. Encoded as CRm = 0b0011.
OSHST
Outer Shareable is the required shareability domain, writes are the required access type, both before and after the barrier instruction. Encoded as CRm = 0b0010.
OSHLD
Outer Shareable is the required shareability domain, reads are the required access type before the barrier instruction, and reads and writes are the required access types after the barrier instruction. Encoded as CRm = 0b0001.

All other encodings of "CRm" that are not listed are reserved and can be encoded using the #<imm> syntax. All unsupported and reserved options must execute as a full system barrier operation, but software must not rely on this behavior. For more information on whether an access is before or after a barrier instruction, see Data Memory Barrier (DMB) or see Data Synchronization Barrier (DSB).

CRm <option>
xx00 RESERVED
0001 OSHLD
0010 OSHST
0011 OSH
0101 NSHLD
0110 NSHST
0111 NSH
1001 ISHLD
1010 ISHST
1011 ISH
1101 LD
1110 ST
1111 SY
<imm>

Is a 4-bit unsigned immediate, in the range 0 to 15, encoded in the "CRm" field.


Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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