← Home

PMMIR: Performance Monitors Machine Identification Register

Purpose

Describes Performance Monitors parameters specific to the implementation to software.

Configuration

This register is present only when EL1 is capable of using AArch32 and FEAT_PMUv3p4 is implemented. Otherwise, direct accesses to PMMIR are UNDEFINED.

Attributes

PMMIR is a 32-bit register.

Field descriptions

313029282726252423222120191817161514131211109876543210
RES0EDGETHWIDTHBUS_WIDTHBUS_SLOTSSLOTS

Bits [31:28]

Reserved, RES0.

EDGE, bits [27:24]

PMU event edge detection. With PMMIR.THWIDTH, indicates implementation of event counter thresholding features.

The value of this field is an IMPLEMENTATION DEFINED choice of:

EDGEMeaning
0b0000

FEAT_PMUv3_EDGE is not implemented.

0b0001

FEAT_PMUv3_EDGE is implemented.

All other values are reserved.

If FEAT_PMUv3_TH is not implemented, the only permitted value is 0b0000.

FEAT_PMUv3_EDGE implements the functionality identified by the value 0b0001.

Note

PMEVTYPER<n>_EL0.TE cannot be accessed through PMEVTYPER<n>.

Access to this field is RO.

THWIDTH, bits [23:20]

PMEVTYPER<n>_EL0.TH width. Indicates implementation of the FEAT_PMUv3_TH feature, and, if implemented, the size of the PMEVTYPER<n>_EL0.TH field.

The value of this field is an IMPLEMENTATION DEFINED choice of:

THWIDTHMeaning
0b0000

FEAT_PMUv3_TH is not implemented.

0b0001

1 bit. PMEVTYPER<n>_EL0.TH[11:1] are RES0.

0b0010

2 bits. PMEVTYPER<n>_EL0.TH[11:2] are RES0.

0b0011

3 bits. PMEVTYPER<n>_EL0.TH[11:3] are RES0.

0b0100

4 bits. PMEVTYPER<n>_EL0.TH[11:4] are RES0.

0b0101

5 bits. PMEVTYPER<n>_EL0.TH[11:5] are RES0.

0b0110

6 bits. PMEVTYPER<n>_EL0.TH[11:6] are RES0.

0b0111

7 bits. PMEVTYPER<n>_EL0.TH[11:7] are RES0.

0b1000

8 bits. PMEVTYPER<n>_EL0.TH[11:8] are RES0.

0b1001

9 bits. PMEVTYPER<n>_EL0.TH[11:9] are RES0.

0b1010

10 bits. PMEVTYPER<n>_EL0.TH[11:10] are RES0.

0b1011

11 bits. PMEVTYPER<n>_EL0.TH[11] is RES0.

0b1100

12 bits.

All other values are reserved.

If FEAT_PMUv3_TH is not implemented, this field is zero.

Otherwise, the largest value that can be written to PMEVTYPER<n>_EL0.TH is 2(PMMIR.THWIDTH) minus one.

Note

PMEVTYPER<n>_EL0.TH cannot be accessed through PMEVTYPER<n>.

Access to this field is RO.

BUS_WIDTH, bits [19:16]

Bus width. Indicates the number of bytes each BUS_ACCESS event relates to. Encoded as Log2(number of bytes), plus one.

The value of this field is an IMPLEMENTATION DEFINED choice of:

BUS_WIDTHMeaning
0b0000

The information is not available.

0b0011

Four bytes.

0b0100

8 bytes.

0b0101

16 bytes.

0b0110

32 bytes.

0b0111

64 bytes.

0b1000

128 bytes.

0b1001

256 bytes.

0b1010

512 bytes.

0b1011

1024 bytes.

0b1100

2048 bytes.

All other values are reserved.

Each transfer is up to this number of bytes. An access might be smaller than the bus width.

When this field is nonzero, each access counted by BUS_ACCESS is at most BUS_WIDTH bytes. An implementation might treat a wide bus as multiple narrower buses, such that a wide access on the bus increments the BUS_ACCESS counter by more than one.

Access to this field is RO.

BUS_SLOTS, bits [15:8]

Bus count. The largest value by which the BUS_ACCESS event might increment in a single BUS_CYCLES cycle.

When this field is nonzero, the largest value by which the BUS_ACCESS event might increment in a single BUS_CYCLES cycle is BUS_SLOTS.

If the bus count information is not available, this field will read as zero.

This field has an IMPLEMENTATION DEFINED value.

Access to this field is RO.

SLOTS, bits [7:0]

Operation width. The largest value by which the STALL_SLOT event might increment by in a single cycle. If the STALL_SLOT event is not implemented, this field might read as zero.

This field has an IMPLEMENTATION DEFINED value.

Access to this field is RO.

Accessing PMMIR

Accesses to this register use the following encodings in the System register encoding space:

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b10010b11100b110

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then UNDEFINED; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T9 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T9 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.TPM == '1' then AArch32.TakeHypTrapException(0x03); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x03); else R[t] = PMMIR; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x03); else R[t] = PMMIR; elsif PSTATE.EL == EL3 then R[t] = PMMIR;