Base Instructions | SIMD&FP Instructions | SVE Instructions | SME Instructions | Index by Encoding | Shared Pseudocode | Proprietary Notice

## SMSTOP

Disables access to Streaming SVE mode and SME architectural state.

SMSTOP exits Streaming SVE mode, and disables the SME ZA storage.

SMSTOP SM exits Streaming SVE mode, but does not disable the SME ZA storage.

SMSTOP ZA disables the SME ZA storage, but does not cause an exit from Streaming SVE mode.

This is an alias of MSR (immediate). This means:

- The encodings in this description are named to match the encodings of MSR (immediate).
- The description of MSR (immediate) gives the operational pseudocode, any constrained unpredictable behavior, and any operational information for this instruction.

### System
(FEAT_SME)

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
1 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | x | x | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1
|  |  | op1 |  | CRm | op2 |

####

SMSTOP {<option>}

is equivalent to

MSR <pstatefield>, #0

and is always the preferred disassembly.

### Assembler Symbols

<option> | Is an optional mode, encoded in CRm<2:1>:
CRm<2:1> | <option>
--- | ---
00 | RESERVED
01 | SM
10 | ZA
11 | [no specifier]

<pstatefield> | Is a PSTATE field name. For the MSR instruction, this is encoded in op1:op2:CRm:
op1 | op2 | CRm | <pstatefield> | Architectural Feature
--- | --- | --- | --- | ---
000 | 00x | xxxx | SEE PSTATE | -
000 | 010 | xxxx | SEE PSTATE | -
000 | 011 | xxxx | UAO | FEAT_UAO
000 | 100 | xxxx | PAN | FEAT_PAN
000 | 101 | xxxx | SPSel | -
000 | 11x | xxxx | RESERVED | -
001 | 000 | 000x | ALLINT | FEAT_NMI
001 | 000 | 001x | PM | FEAT_EBEP
001 | 000 | 01xx | RESERVED | -
001 | 000 | 1xxx | RESERVED | -
001 | 001 | xxxx | RESERVED | -
001 | 01x | xxxx | RESERVED | -
001 | 1xx | xxxx | RESERVED | -
010 | xxx | xxxx | RESERVED | -
011 | 000 | xxxx | RESERVED | -
011 | 001 | xxxx | SSBS | FEAT_SSBS
011 | 010 | xxxx | DIT | FEAT_DIT
011 | 011 | 000x | RESERVED | -
011 | 011 | 001x | SVCRSM | FEAT_SME
011 | 011 | 010x | SVCRZA | FEAT_SME
011 | 011 | 011x | SVCRSMZA | FEAT_SME
011 | 011 | 1xxx | RESERVED | -
011 | 100 | xxxx | TCO | FEAT_MTE
011 | 101 | xxxx | RESERVED | -
011 | 110 | xxxx | DAIFSet | -
011 | 111 | xxxx | DAIFClr | -
1xx | xxx | xxxx | RESERVED | -
For the SMSTART and SMSTOP aliases, this is encoded in "CRm<2:1>", where 0b01 specifies SVCRSM, 0b10 specifies SVCRZA, and 0b11 specifies SVCRSMZA.

### Operation

The description of MSR (immediate) gives the operational pseudocode for this instruction.

Base Instructions | SIMD&FP Instructions | SVE Instructions | SME Instructions | Index by Encoding | Shared Pseudocode | Proprietary Notice

Internal version only: isa v33.74, AdvSIMD v29.23, pseudocode v2023-09_rel, sve v2023-09_rc3 ; Build timestamp: 2023-09-27T17:06

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