Kernel Crate Boundaries

Relevant source files

kernel/crates/kernel_* and kernel/src have different ownership roles, and a pair must never independently implement the same policy or state transition.

Boundary rules

kernel/crates/kernel_* holds reusable, policy-free contracts and host-testable algorithms where practical.
kernel/src composes those contracts with architecture, process, scheduler, memory and device integration.
A crate is canonical when its public contract is consumed directly by both host tests and kernel integration; kernel/src then supplies adapters only.
A kernel/src module is canonical when it owns platform state or lifecycle; a similarly named crate must stay a narrow contract or be retired.
Error, ownership, rollback, protection and fault semantics belong in the canonical layer and must not be silently weakened by an adapter.
New extraction work must name the canonical side, list the adapter boundary, and add a static or host test that prevents duplicate policy from returning.

Integration pairs

Reusable contract	Kernel integration
`kernel_syscall`	`kernel/src/syscall/`
`kernel_virtual_memory`	`kernel/src/mem/`
`kernel_device`	`kernel/src/driver/` and architecture platform code
`kernel_elfloader`	process exec / image loading
`kernel_map_transaction`	address-space and heap mapping
`kernel_run_queue`	scheduler task ownership and CPU selection
`kernel_usermem`	`kernel/src/syscall/validation.rs` (user-copy adapter)

Crate inventory

Roles and gates come from the generated component inventory .

Crate	Role	Required gate
`kernel_abi`	Public userspace ABI (syscall numbers, errno, BPF command and attach numbers, `fcntl`, `mman`, time, uio)	host lint and tests
`kernel_bpf`	BPF runtime: loader, verifier, maps, interpreter, signing, profiles, attach, actuation	cloud/embedded lint, tests, Miri
`kernel_devfs`	Device filesystem (`/dev`)	host lint and tests
`kernel_device`	Device contracts (block, raw)	host lint and tests
`kernel_elfloader`	ELF loader	host lint, tests, fuzz
`kernel_map_transaction`	`map_range` rollback bookkeeping	host lint and tests
`kernel_memapi`	Mapped-memory contract	host lint and tests (interface-only)
`kernel_pci`	PCI configuration contracts	host lint and tests
`kernel_physical_memory`	Sparse physical frame manager, fault injection	host lint and tests
`kernel_run_queue`	Per-CPU runnable queue core (Cordyceps MPSC queues, bounded steal)	host lint, tests, Loom model
`kernel_syscall`	Syscall contracts (access, fcntl, malloc, mman, stat, unistd, user pointers)	host lint and tests
`kernel_time`	Clock conversion and deadline queues	host lint and tests
`kernel_usermem`	Fault-safe user-memory access contract (audit finding C-01)	host lint and tests
`kernel_vfs`	Virtual filesystem and path types	host lint and tests
`kernel_virtual_memory`	Virtual-memory segment allocator	host lint and tests
`shrike_link`	Pi 5 to Shrike-lite UART control-link codec, session, watchdog (`no_std`, zero-dep)	host lint and tests

kernel/crates/kernel_wait_channel_tests contains host tests for the wait-channel protocol; it has no library crate of its own.

Naming contract

Prefix / suffix	Meaning
`kernel_*`	Internal reusable kernel crate
`axiom_` / `axiomos-`	Host-side repository or shipped axiomos tooling
`rk_*`	Runtime-kit tools and services
`shrike_*`	Hardware or firmware components
`*_demo`	Demonstration program or crate
`*_bench`	Benchmark program or crate