# PORT-ABI requirements

::::{req} No EmbCC-specific extension in the public API
:id: PORT-ABI-001
:status: Accepted
:evidence: not evaluated
:design_source: requirements/PORT.md

The public kernel API shall not require an EmbCC-specific language extension.

**Rationale:** GCC and Clang builds are first-class (ADR-023).

**Status:** Accepted 2026-10-07

**Verification:** Build matrix: public headers compile with `-std=c11 -pedantic` on GCC and Clang.

**Trace:** SPEC-011 §15; SPEC-001 §10; v0.1 §21.5

[Normative source](../../requirements/PORT.md).

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::::{req} Portability layer for attributes and builtins
:id: PORT-ABI-002
:status: Accepted
:evidence: not evaluated
:design_source: requirements/PORT.md

Compiler-specific attributes and builtins shall be isolated behind portability interfaces.

**Rationale:** No compiler conditionals scattered through generic code (v0.1 §21.2).

**Status:** Accepted 2026-10-07

**Verification:** Analysis: CI grep rejects `__attribute__` and `__builtin_` outside `include/emb/compiler/` and `arch/`.

**Trace:** SPEC-011 §15; SPEC-001 §10

[Normative source](../../requirements/PORT.md).

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::::{req} Documented and tested compiler matrix
:id: PORT-ABI-003
:status: Accepted
:evidence: not evaluated
:design_source: requirements/PORT.md

Supported compiler and version combinations shall be documented and continuously tested where infrastructure permits.

**Rationale:** Support is stated per architecture and version, not claimed globally (v0.1 §21.3).

**Status:** Accepted 2026-10-07

**Verification:** Analysis: the matrix of 09 §11 is generated from CI results each release.

**Trace:** 09 §11; 05 §2

[Normative source](../../requirements/PORT.md).

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::::{req} Early detection of incompatible combinations
:id: PORT-ABI-004
:status: Accepted
:evidence: not evaluated
:design_source: requirements/PORT.md

The build shall detect incompatible architecture, ABI, and configuration combinations as early as practical.

**Rationale:** A refused configuration beats a wrong image.

**Status:** Accepted 2026-10-07

**Verification:** Build tests: hard-float and soft-float mix, a kernel feature the port manifest lacks, a profile the port cannot support, each fails at configuration.

**Trace:** SPEC-011 §2; BLD-007

[Normative source](../../requirements/PORT.md).

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::::{req} Optimizations never change semantics
:id: PORT-ABI-005
:status: Accepted
:evidence: not evaluated
:design_source: requirements/PORT.md

Toolchain-specific optimizations may improve performance but shall not change documented kernel semantics.

**Rationale:** One conformance suite across compilers and optimization levels.

**Status:** Accepted 2026-10-07

**Verification:** The conformance suite runs at `-O0`, `-Os`, and `-O2` on every compiler of the matrix.

**Trace:** 05 §4; 09 §7

[Normative source](../../requirements/PORT.md).

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