CNTKCTL, Counter-timer Kernel Control register

The CNTKCTL characteristics are:

Purpose

Controls the generation of an event stream from the virtual counter, and access from EL0 modes to the physical counter, virtual counter, EL1 physical timers, and the virtual timer.

Configuration

AArch32 System register CNTKCTL bits [31:0] are architecturally mapped to AArch64 System register CNTKCTL_EL1[31:0] .

RW fields in this register reset to architecturally UNKNOWN values.

Attributes

CNTKCTL is a 32-bit register.

Field descriptions

The CNTKCTL bit assignments are:

Bits [31:18]

Reserved, RES0.

EVNTIS, bit [17]

When ARMv8.6-ECV is implemented:

Controls the scale of the generation of the event stream.

This control applies regardless of the value of the CNTHCTL_EL2.ECV bit.

This field resets to an architecturally UNKNOWN value.

Otherwise:

Reserved, RES0.

Bits [16:10]

Reserved, RES0.

PL0PTEN, bit [9]

Traps PL0 accesses to the physical timer registers to Undefined mode.

This field resets to an architecturally UNKNOWN value.

PL0VTEN, bit [8]

Traps PL0 accesses to the virtual timer registers to Undefined mode.

This field resets to an architecturally UNKNOWN value.

EVNTI, bits [7:4]

Selects which bit (0 to 15) of the counter register CNTVCT is the trigger for the event stream generated from that counter, when that stream is enabled.

This field resets to an architecturally UNKNOWN value.

EVNTDIR, bit [3]

Controls which transition of the counter register CNTVCT trigger bit, defined by EVNTI, generates an event when the event stream is enabled:

This field resets to an architecturally UNKNOWN value.

EVNTEN, bit [2]

Enables the generation of an event stream from the counter register CNTVCT:

This field resets to an architecturally UNKNOWN value.

PL0VCTEN, bit [1]

Traps PL0 accesses to the frequency register and virtual counter register to Undefined mode.

This field resets to an architecturally UNKNOWN value.

PL0PCTEN, bit [0]

Traps PL0 accesses to the frequency register and physical counter register to Undefined mode.

This field resets to an architecturally UNKNOWN value.

if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    return CNTKCTL;
elsif PSTATE.EL == EL2 then
    return CNTKCTL;
elsif PSTATE.EL == EL3 then
    return CNTKCTL;
              

if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    CNTKCTL = R[t];
elsif PSTATE.EL == EL2 then
    CNTKCTL = R[t];
elsif PSTATE.EL == EL3 then
    CNTKCTL = R[t];