요약·해설과 원문, 전문 번역을 서로 분리했습니다. API 이름, symbol, source path는 원문 표기를 사용합니다.
1. 요약·해설
원문의 핵심 논리와 kernel programming 관점의 보충 설명입니다. 아래의 전문 번역과는 별도로 작성했습니다.
2. 영어 원문 전체
번역 기준이 된 Linux v6.18.37 원문입니다. 줄 번호는 이 버전의 파일 좌표입니다.
원문 전체 펼치기
IBM Power-Management Bindings
=============================
Linux running on baremetal POWER machines has access to the processor
idle states. The description of these idle states is exposed via the
node @power-mgt in the device-tree by the firmware.
Definitions:
----------------
Typically each idle state has the following associated properties:
- name: The name of the idle state as defined by the firmware.
- flags: indicating some aspects of this idle states such as the
extent of state-loss, whether timebase is stopped on this
idle states and so on. The flag bits are as follows:
- exit-latency: The latency involved in transitioning the state of the
CPU from idle to running.
- target-residency: The minimum time that the CPU needs to reside in
this idle state in order to accrue power-savings
benefit.
Properties
----------------
The following properties provide details about the idle states. These
properties are exposed as arrays. Each entry in the property array
provides the value of that property for the idle state associated with
the array index of that entry.
If idle-states are defined, then the properties
"ibm,cpu-idle-state-names" and "ibm,cpu-idle-state-flags" are
required. The other properties are required unless mentioned
otherwise. The length of all the property arrays must be the same.
- ibm,cpu-idle-state-names:
Array of strings containing the names of the idle states.
- ibm,cpu-idle-state-flags:
Array of unsigned 32-bit values containing the values of the
flags associated with the aforementioned idle-states. The
flag bits are as follows:
0x00000001 /* Decrementer would stop */
0x00000002 /* Needs timebase restore */
0x00001000 /* Restore GPRs like nap */
0x00002000 /* Restore hypervisor resource from PACA pointer */
0x00004000 /* Program PORE to restore PACA pointer */
0x00010000 /* This is a nap state (POWER7,POWER8) */
0x00020000 /* This is a fast-sleep state (POWER8)*/
0x00040000 /* This is a winkle state (POWER8) */
0x00080000 /* This is a fast-sleep state which requires a */
/* software workaround for restoring the */
/* timebase (POWER8) */
0x00800000 /* This state uses SPR PMICR instruction */
/* (POWER8)*/
0x00100000 /* This is a fast stop state (POWER9) */
0x00200000 /* This is a deep-stop state (POWER9) */
- ibm,cpu-idle-state-latencies-ns:
Array of unsigned 32-bit values containing the values of the
exit-latencies (in ns) for the idle states in
ibm,cpu-idle-state-names.
- ibm,cpu-idle-state-residency-ns:
Array of unsigned 32-bit values containing the values of the
target-residency (in ns) for the idle states in
ibm,cpu-idle-state-names. On POWER8 this is an optional
property. If the property is absent, the target residency for
the "Nap", "FastSleep" are defined to 10000 and 300000000
respectively by the kernel. On POWER9 this property is required.
- ibm,cpu-idle-state-psscr:
Array of unsigned 64-bit values containing the values for the
PSSCR for each of the idle states in ibm,cpu-idle-state-names.
This property is required on POWER9 and absent on POWER8.
- ibm,cpu-idle-state-psscr-mask:
Array of unsigned 64-bit values containing the masks
indicating which psscr fields are set in the corresponding
entries of ibm,cpu-idle-state-psscr. This property is
required on POWER9 and absent on POWER8.
Whenever the firmware sets an entry in
ibm,cpu-idle-state-psscr-mask value to 0xf, it implies that
only the Requested Level (RL) field of the corresponding entry
in ibm,cpu-idle-state-psscr should be considered by the
kernel. For such idle states, the kernel would set the
remaining fields of the psscr to the following sane-default
values.
- ESL and EC bits are to 1. So wakeup from any stop
state will be at vector 0x100.
- MTL and PSLL are set to the maximum allowed value as
per the ISA, i.e. 15.
- The Transition Rate, TR is set to the Maximum value
3.
For all the other values of the entry in
ibm,cpu-idle-state-psscr-mask, the kernel expects all the
psscr fields of the corresponding entry in
ibm,cpu-idle-state-psscr to be correctly set by the firmware.
- ibm,cpu-idle-state-pmicr:
Array of unsigned 64-bit values containing the pmicr values
for the idle states in ibm,cpu-idle-state-names. This 64-bit
register value is to be set in pmicr for the corresponding
state if the flag indicates that pmicr SPR should be set. This
is an optional property on POWER8 and is absent on
POWER9.
- ibm,cpu-idle-state-pmicr-mask:
Array of unsigned 64-bit values containing the mask indicating
which of the fields of the PMICR are set in the corresponding
entries in ibm,cpu-idle-state-pmicr. This is an optional
property on POWER8 and is absent on POWER9.
3. 한국어 전문 번역
영어 원문의 문단 순서와 의미를 유지한 전체 번역입니다. 코드, 함수명, symbol과 URL은 원문 표기를 유지합니다.
POWER idle-state 정의
1-24Bare-metal POWER machine의 Linux는 processor idle state에 접근하며 firmware는 device tree의 `@power-mgt` node로 이를 노출합니다. 각 state에는 firmware가 정한 `name`, state-loss·timebase stop 등을 나타내는 `flags`, idle에서 running으로 전환하는 `exit-latency`, power saving을 얻기 위한 최소 체류 시간 `target-residency`가 연결됩니다.
Idle-state 배열과 flag
25-59Property는 배열이며 같은 index의 entry들이 하나의 idle state를 설명합니다. Idle state가 있으면 `ibm,cpu-idle-state-names`와 `ibm,cpu-idle-state-flags`가 필수이고, 별도 언급이 없는 다른 property도 필수입니다. 모든 배열 길이는 같아야 합니다.
`ibm,cpu-idle-state-names`는 이름 string 배열이고 `ibm,cpu-idle-state-flags`는 u32 flag 배열입니다.
| Flag | 의미 |
|---|---|
| 0x00000001 | Decrementer stop |
| 0x00000002 | Timebase restore 필요 |
| 0x00001000 | Nap처럼 GPR restore |
| 0x00002000 | PACA pointer에서 hypervisor resource restore |
| 0x00004000 | PACA pointer restore를 위해 PORE program |
| 0x00010000 | POWER7·POWER8 nap state |
| 0x00020000 | POWER8 fast-sleep state |
| 0x00040000 | POWER8 winkle state |
| 0x00080000 | Timebase restore software workaround가 필요한 POWER8 fast-sleep |
| 0x00800000 | POWER8 SPR PMICR instruction 사용 |
| 0x00100000 | POWER9 fast stop state |
| 0x00200000 | POWER9 deep-stop state |
Latency·residency·PSSCR
60-83`ibm,cpu-idle-state-latencies-ns`는 state별 u32 exit latency를 ns로 담습니다. `ibm,cpu-idle-state-residency-ns`는 u32 target residency를 ns로 담으며 POWER8에서는 선택, POWER9에서는 필수입니다. POWER8에서 없으면 kernel은 Nap을 10000, FastSleep을 300000000으로 정합니다.
`ibm,cpu-idle-state-psscr`는 state별 u64 PSSCR 값이고 `ibm,cpu-idle-state-psscr-mask`는 대응 PSSCR에서 설정된 field를 나타내는 u64 mask입니다. 둘 다 POWER9에서는 필수이고 POWER8에는 없습니다.
PSSCR mask 기본값
84-105Firmware가 `ibm,cpu-idle-state-psscr-mask` entry를 0xf로 설정하면 kernel은 대응 PSSCR의 Requested Level(RL)만 고려합니다. 나머지 field는 ESL·EC=1로 두어 stop-state wakeup vector를 0x100으로 하고, MTL·PSLL은 ISA 최대값 15, Transition Rate(TR)는 최대값 3으로 설정합니다.
Mask entry가 0xf가 아니면 kernel은 대응 `ibm,cpu-idle-state-psscr`의 모든 field가 firmware에 의해 올바르게 설정되어 있다고 기대합니다.
POWER8 PMICR
106-118`ibm,cpu-idle-state-pmicr`는 flag가 PMICR SPR 설정을 요구할 때 state별로 PMICR에 쓸 u64 값을 담습니다. `ibm,cpu-idle-state-pmicr-mask`는 대응 PMICR entry에서 설정된 field를 나타내는 u64 mask입니다. 둘 다 POWER8에서는 선택 property이고 POWER9에는 없습니다.
요약과 해설
power-mgt.txt:1-118Idle-state 배열 index와 generation별 register 차이를 정리합니다.