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# TRCVISSCTLR, Trace ViewInst Start/Stop Control Register

The TRCVISSCTLR characteristics are:

## Purpose

Use this to select, or read, the Single Address Comparators for the ViewInst start/stop function.

## Configuration

External register TRCVISSCTLR bits [31:0] are architecturally mapped to AArch64 System register TRCVISSCTLR[31:0].

This register is present only when FEAT_ETE is implemented, FEAT_TRC_EXT is implemented and UInt(TRCIDR4.NUMACPAIRS) > 0. Otherwise, direct accesses to TRCVISSCTLR are RES0.

## Attributes

TRCVISSCTLR is a 32-bit register.

## Field descriptions

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
STOP[15] | STOP[14] | STOP[13] | STOP[12] | STOP[11] | STOP[10] | STOP[9] | STOP[8] | STOP[7] | STOP[6] | STOP[5] | STOP[4] | STOP[3] | STOP[2] | STOP[1] | STOP[0] | START[15] | START[14] | START[13] | START[12] | START[11] | START[10] | START[9] | START[8] | START[7] | START[6] | START[5] | START[4] | START[3] | START[2] | START[1] | START[0]

#### STOP[<m>], bit [m+16], for m = 15 to 0

Selects whether Single Address Comparator <m> is used with the ViewInst start/stop function for the purpose of stopping trace.

STOP[<m>] | Meaning
--- | ---
0b0 | The Single Address Comparator <m> is not selected as a stop resource.
0b1 | The Single Address Comparator <m> is selected as a stop resource.

The reset behavior of this field is:

- On a Trace unit reset, this field resets to an architecturally UNKNOWN value.

Accessing this field has the following behavior:

- When m >= UInt(TRCIDR4.NUMACPAIRS) * 2, access to this field is RES0 .
- Otherwise, access to this field is RW.

#### START[<m>], bit [m], for m = 15 to 0

Selects whether Single Address Comparator <m> is used with the ViewInst start/stop function for the purpose of starting trace.

START[<m>] | Meaning
--- | ---
0b0 | The Single Address Comparator <m> is not selected as a start resource.
0b1 | The Single Address Comparator <m> is selected as a start resource.

The reset behavior of this field is:

- On a Trace unit reset, this field resets to an architecturally UNKNOWN value.

Accessing this field has the following behavior:

- When m >= UInt(TRCIDR4.NUMACPAIRS) * 2, access to this field is RES0 .
- Otherwise, access to this field is RW.

## Accessing TRCVISSCTLR

Must be programmed if TRCIDR4.NUMACPAIRS > 0b0000.

For any 2 comparators selected for the ViewInst start/stop function, the comparator containing the lower address must be a lower numbered comparator.

Writes are CONSTRAINED UNPREDICTABLE if the trace unit is not in the Idle state.

#### TRCVISSCTLR can be accessed through the external debug interface:

Component | Offset | Instance
--- | --- | ---
ETE | 0x088 | TRCVISSCTLR

This interface is accessible as follows:

- When OSLockStatus(), or !AllowExternalTraceAccess() or !IsTraceCorePowered(), accesses to this register generate an error response.
- Otherwise, accesses to this register are RW.

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6

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