Low Power / UPF · All levels
Isolation & Retention
Isolation policies, retention registers, save/restore sequencing, and wake-up correctness under real mode transitions.
Section goal
Isolation policies, retention registers, save/restore sequencing, and wake-up correctness under real mode transitions.
How to study this section
Start with each topic hub and sketch the domain/state model.
Use mechanism and reports pages to connect policy intent to evidence.
Practice debug and worked-example pages for review readiness.
Close with checklist and silicon impact before signoff discussions.
Topics
isolation-strategies/ — Isolation Strategies
retention-register-design/ — Retention Register Design
save-restore-sequencing/ — Save/Restore Sequencing
isolation-debug/ — Isolation Debug
Related topics
Low-power deep dive
Isolation and retention are sequence-sensitive contracts, not static checkboxes.
Concept diagram
SEQUENCE
save -> isolate -> power-off -> power-on -> restore -> releaseMetric graph
TRANSITION DEFECT MIX
polarity errors ███████
late iso assertion █████
restore ordering ████Reports and artifacts
isolation crossing report
retention list
save/restore timing
X-propagation log
Mini case study
A late isolation enable caused intermittent X leaks only on one PMU path.
Debug branches
Validate control polarity
Trace AON source
Replay transition waveform
Senior review question
Ask: what transition evidence proves this topic is closed, and which owner signs it?
Execution drill pack 1
Use this pack to rehearse low-power closure on low-power/isolation-retention: transition framing, policy ownership, implementation evidence, and release confidence.
Transition checklist
State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.
Review prompts
Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?
Evidence capsule
LP EVIDENCE CAPSULE 1
PATH: low-power/isolation-retention
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>Execution drill pack 2
Use this pack to rehearse low-power closure on low-power/isolation-retention: transition framing, policy ownership, implementation evidence, and release confidence.
Transition checklist
State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.
Review prompts
Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?
Evidence capsule
LP EVIDENCE CAPSULE 2
PATH: low-power/isolation-retention
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>Execution drill pack 3
Use this pack to rehearse low-power closure on low-power/isolation-retention: transition framing, policy ownership, implementation evidence, and release confidence.
Transition checklist
State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.
Review prompts
Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?
Evidence capsule
LP EVIDENCE CAPSULE 3
PATH: low-power/isolation-retention
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>Execution drill pack 4
Use this pack to rehearse low-power closure on low-power/isolation-retention: transition framing, policy ownership, implementation evidence, and release confidence.
Transition checklist
State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.
Review prompts
Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?
Evidence capsule
LP EVIDENCE CAPSULE 4
PATH: low-power/isolation-retention
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>Execution drill pack 5
Use this pack to rehearse low-power closure on low-power/isolation-retention: transition framing, policy ownership, implementation evidence, and release confidence.
Transition checklist
State transition explicitly named with legal source/target states.
Crossing and domain ownership are mapped and agreed.
Policy controls are traced to always-on source logic.
Waveform bookmarks align controls with state timestamps.
Review prompts
Which policy object is first to deviate from intent?
Which owner can apply the smallest reversible fix?
What regression matrix proves no collateral damage?
Which waiver conditions would still block release?
Evidence capsule
LP EVIDENCE CAPSULE 5
PATH: low-power/isolation-retention
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>