Low Power / UPF · All levels

Isolation Strategies: Software / Programmer View

Software / Programmer View for Isolation Strategies.

RTL / PMU / firmware view

Reset and control protocols determine whether restore behavior is deterministic.

What design teams feel

PMU sequence flakiness
unexpected X-propagation
retention restore mismatch

Interface impact

Control signal ownership
reset vs restore ordering
state machine observability

Tool interaction

Synthesis LP insertion assumptions
name stability for UPF bindings

Mitigations

Assert transition order
trace control ownership
freeze interface contracts

diagram

RTL / PMU VIEW — Isolation Strategies
// isolate before switch-off, restore before traffic release

Control ownership layers

diagram

LP OWNERSHIP LAYERS — Isolation Strategies

layer                owns                          typical failure
------------------   ---------------------------   --------------------------
architecture         domain strategy               infeasible power states
UPF intent           policy objects + bindings     wrong/missing policy
implementation       LP cell insertion/routing     illegal physical behavior
verification         transition scenarios          uncovered LP bug
signoff governance   waiver + release decisions    late escape to silicon

Low-power deep dive

Isolation and retention are sequence-sensitive contracts, not static checkboxes.

Concept diagram

diagram

SEQUENCE

save -> isolate -> power-off -> power-on -> restore -> release

Metric graph

diagram

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?

Key takeaways

State transition context must accompany every low-power metric claim.
Intent changes require simulation, formal, and implementation re-validation.

Common pitfalls

Comparing results from mismatched UPF revisions.
Assuming static checks replace transition validation.
Shipping with aged waivers and unclear ownership.

Execution drill pack 1

Use this pack to rehearse low-power closure on low-power/isolation-retention/isolation-strategies/software-programmer-view: 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

diagram

LP EVIDENCE CAPSULE 1

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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

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

diagram

LP EVIDENCE CAPSULE 2

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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

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

diagram

LP EVIDENCE CAPSULE 3

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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

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

diagram

LP EVIDENCE CAPSULE 4

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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

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

diagram

LP EVIDENCE CAPSULE 5

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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 6

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

diagram

LP EVIDENCE CAPSULE 6

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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 7

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

diagram

LP EVIDENCE CAPSULE 7

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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 8

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

diagram

LP EVIDENCE CAPSULE 8

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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 9

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

diagram

LP EVIDENCE CAPSULE 9

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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 10

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

diagram

LP EVIDENCE CAPSULE 10

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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 11

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

diagram

LP EVIDENCE CAPSULE 11

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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 12

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

diagram

LP EVIDENCE CAPSULE 12

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
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 13

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

diagram

LP EVIDENCE CAPSULE 13

PATH: low-power/isolation-retention/isolation-strategies/software-programmer-view
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Principal LP review addendum

Isolation cells clamp outputs from switchable domains before receivers in always-on or differently powered domains sample unknown values.

Metric: unisolated crossing count, isolation enable correctness, and X-propagation escapes

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