mcountinhibit

Machine Counter Inhibit

Bits to inhibit (stops counting) performance counters.

The counter-inhibit register mcountinhibit is a WARL register that controls which of the hardware performance-monitoring counters increment. The settings in this register only control whether the counters increment; their accessibility is not affected by the setting of this register.

When the CY, IR, or HPMn bit in the mcountinhibit register is clear, the mcycle, minstret, or mhpmcountern register increments as usual. When the CY, IR, or HPM_n_ bit is set, the corresponding counter does not increment.

The mcycle CSR may be shared between harts on the same core, in which case the mcountinhibit.CY field is also shared between those harts, and so writes to mcountinhibit.CY will be visible to those harts.

If the mcountinhibit register is not implemented, the implementation behaves as though the register were set to zero.

When the mcycle and minstret counters are not needed, it is desirable to conditionally inhibit them to reduce energy consumption. Providing a single CSR to inhibit all counters also allows the counters to be atomically sampled.

Because the mtime counter can be shared between multiple cores, it cannot be inhibited with the mcountinhibit mechanism.

Attributes

Defining Extension	anyOf: Sm, version >= Sm@1.11.0 Smhpm, version >= Smhpm@1.11.0
CSR Address	0x320
Length	32-bit
Privilege Mode	M

Defining Extension

anyOf:
- Sm, version >= Sm@1.11.0
- Smhpm, version >= Smhpm@1.11.0

CSR Address

0x320

Length

32-bit

Privilege Mode

Format

Figure 1. mcountinhibit format

Field Summary

Name	Location	Reset Value
mcountinhibit.CY	0	UNDEFINED_LEGAL
mcountinhibit.IR	2	UNDEFINED_LEGAL
mcountinhibit.HPM3	3	UNDEFINED_LEGAL
mcountinhibit.HPM4	4	UNDEFINED_LEGAL
mcountinhibit.HPM5	5	UNDEFINED_LEGAL
mcountinhibit.HPM6	6	UNDEFINED_LEGAL
mcountinhibit.HPM7	7	UNDEFINED_LEGAL
mcountinhibit.HPM8	8	UNDEFINED_LEGAL
mcountinhibit.HPM9	9	UNDEFINED_LEGAL
mcountinhibit.HPM10	10	UNDEFINED_LEGAL
mcountinhibit.HPM11	11	UNDEFINED_LEGAL
mcountinhibit.HPM12	12	UNDEFINED_LEGAL
mcountinhibit.HPM13	13	UNDEFINED_LEGAL
mcountinhibit.HPM14	14	UNDEFINED_LEGAL
mcountinhibit.HPM15	15	UNDEFINED_LEGAL
mcountinhibit.HPM16	16	UNDEFINED_LEGAL
mcountinhibit.HPM17	17	UNDEFINED_LEGAL
mcountinhibit.HPM18	18	UNDEFINED_LEGAL
mcountinhibit.HPM19	19	UNDEFINED_LEGAL
mcountinhibit.HPM20	20	UNDEFINED_LEGAL
mcountinhibit.HPM21	21	UNDEFINED_LEGAL
mcountinhibit.HPM22	22	UNDEFINED_LEGAL
mcountinhibit.HPM23	23	UNDEFINED_LEGAL
mcountinhibit.HPM24	24	UNDEFINED_LEGAL
mcountinhibit.HPM25	25	UNDEFINED_LEGAL
mcountinhibit.HPM26	26	UNDEFINED_LEGAL
mcountinhibit.HPM27	27	UNDEFINED_LEGAL
mcountinhibit.HPM28	28	UNDEFINED_LEGAL
mcountinhibit.HPM29	29	UNDEFINED_LEGAL
mcountinhibit.HPM30	30	UNDEFINED_LEGAL
mcountinhibit.HPM31	31	UNDEFINED_LEGAL

Name

Location

Type

Reset Value

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

UNDEFINED_LEGAL

Fields

`CY`

Location: 0
Description: When set, mcycle.COUNT stops counting in all privilege modes.
Type
Reset value: UNDEFINED_LEGAL

`IR`

Location: 2
Description: When set, minstret.COUNT stops counting in all privilege modes.
Type
Reset value: UNDEFINED_LEGAL

`HPM3`

Location: 3
Description

When set, hpmcounter3.COUNT stops counting in all privilege modes.

Since hpmcounter3 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM4`

Location: 4
Description

When set, hpmcounter4.COUNT stops counting in all privilege modes.

Since hpmcounter4 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM5`

Location: 5
Description

When set, hpmcounter5.COUNT stops counting in all privilege modes.

Since hpmcounter5 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM6`

Location: 6
Description

When set, hpmcounter6.COUNT stops counting in all privilege modes.

Since hpmcounter6 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM7`

Location: 7
Description

When set, hpmcounter7.COUNT stops counting in all privilege modes.

Since hpmcounter7 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM8`

Location: 8
Description

When set, hpmcounter8.COUNT stops counting in all privilege modes.

Since hpmcounter8 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM9`

Location: 9
Description

When set, hpmcounter9.COUNT stops counting in all privilege modes.

Since hpmcounter9 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM10`

Location: 10
Description

When set, hpmcounter10.COUNT stops counting in all privilege modes.

Since hpmcounter10 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM11`

Location: 11
Description

When set, hpmcounter11.COUNT stops counting in all privilege modes.

Since hpmcounter11 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM12`

Location: 12
Description

When set, hpmcounter12.COUNT stops counting in all privilege modes.

Since hpmcounter12 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM13`

Location: 13
Description

When set, hpmcounter13.COUNT stops counting in all privilege modes.

Since hpmcounter13 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM14`

Location: 14
Description

When set, hpmcounter14.COUNT stops counting in all privilege modes.

Since hpmcounter14 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM15`

Location: 15
Description

When set, hpmcounter15.COUNT stops counting in all privilege modes.

Since hpmcounter15 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM16`

Location: 16
Description

When set, hpmcounter16.COUNT stops counting in all privilege modes.

Since hpmcounter16 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM17`

Location: 17
Description

When set, hpmcounter17.COUNT stops counting in all privilege modes.

Since hpmcounter17 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM18`

Location: 18
Description

When set, hpmcounter18.COUNT stops counting in all privilege modes.

Since hpmcounter18 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM19`

Location: 19
Description

When set, hpmcounter19.COUNT stops counting in all privilege modes.

Since hpmcounter19 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM20`

Location: 20
Description

When set, hpmcounter20.COUNT stops counting in all privilege modes.

Since hpmcounter20 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM21`

Location: 21
Description

When set, hpmcounter21.COUNT stops counting in all privilege modes.

Since hpmcounter21 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM22`

Location: 22
Description

When set, hpmcounter22.COUNT stops counting in all privilege modes.

Since hpmcounter22 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM23`

Location: 23
Description

When set, hpmcounter23.COUNT stops counting in all privilege modes.

Since hpmcounter23 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM24`

Location: 24
Description

When set, hpmcounter24.COUNT stops counting in all privilege modes.

Since hpmcounter24 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM25`

Location: 25
Description

When set, hpmcounter25.COUNT stops counting in all privilege modes.

Since hpmcounter25 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM26`

Location: 26
Description

When set, hpmcounter26.COUNT stops counting in all privilege modes.

Since hpmcounter26 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM27`

Location: 27
Description

When set, hpmcounter27.COUNT stops counting in all privilege modes.

Since hpmcounter27 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM28`

Location: 28
Description

When set, hpmcounter28.COUNT stops counting in all privilege modes.

Since hpmcounter28 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM29`

Location: 29
Description

When set, hpmcounter29.COUNT stops counting in all privilege modes.

Since hpmcounter29 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM30`

Location: 30
Description

When set, hpmcounter30.COUNT stops counting in all privilege modes.

Since hpmcounter30 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL

`HPM31`

Location: 31
Description

When set, hpmcounter31.COUNT stops counting in all privilege modes.

Since hpmcounter31 is not implemented, this field is read-only zero.

Type
Reset value: UNDEFINED_LEGAL