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# DC IGDVAC, Data, Allocation Tag or unified Cache line Invalidate of Allocation Tags by VA to PoC

The DC IGDVAC characteristics are:

## Purpose

Invalidate data and Allocation Tags in data cache by address to Point of Coherency.

## Configuration

This instruction is present only when ARMv8.5-MemTag is implemented. Otherwise, direct accesses to DC IGDVAC are UNDEFINED.

## Attributes

DC IGDVAC is a 64-bit System instruction.

## Field descriptions

The DC IGDVAC input value bit assignments are:

63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32
Virtual address to use
Virtual address to use
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

#### Bits [63:0]

Virtual address to use. No alignment restrictions apply to this VA.

## Executing the DC IGDVAC instruction

When the instruction is executed, it can generate a watchpoint, which is prioritized in the same way as other watchpoints. If a watchpoint is generated, the CM bit in the ESR_ELx.ISS field is set to 1.

This instruction requires write access permission to the VA, otherwise it generates a Permission Fault, subject to the constraints described in 'Permission fault' in the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

Execution of this instruction might require an address translation from VA to PA, and that translation might fault. For more information, see 'The data cache maintenance instruction (DC)' in the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

Accesses to this instruction use the following encodings:

#### DC IGDVAC, <Xt>

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b01 | 0b000 | 0b0111 | 0b0110 | 0b101

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<DC,VM> != '00' then DC_CIGDVAC(X[t]); else DC_IGDVAC(X[t]); elsif PSTATE.EL == EL2 then DC_IGDVAC(X[t]); elsif PSTATE.EL == EL3 then DC_IGDVAC(X[t]);

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27/03/2019 21:59; e5e4db499bf9867a4b93324c4dbac985d3da9376

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