IPC

Anonymous and named pipes on Peios — pipe/pipe2/FIFO syscalls, packet mode, the splice family, and how filesystem SDs gate FIFOs.

Unix domain sockets on Peios — socket types, the three address forms, and the security implications of the abstract namespace.

Peer authentication on Unix sockets — the SO_PEERCRED family, the new SO_PEERTOKEN and SO_PEERGUID, and the recommended Peios authentication patterns.

Passing file descriptors between processes on Peios via SCM_RIGHTS — the fd-bearer-authority model and its security implications.

System V IPC on Peios — semaphores, message queues, shared memory, and the security descriptor model that replaces the legacy ipc_perm 9-bit mode.

POSIX IPC primitives on Peios — POSIX semaphores, POSIX message queues, and how they inherit access control from their backing filesystems.

File descriptors that deliver kernel events on Peios — eventfd, signalfd, timerfd, pidfd, and the access-controlled cross-process pidfd_getfd primitive.

File-descriptor readiness on Peios — epoll, poll, select, and the patterns for high-throughput event-driven services.

io_uring on Peios — the shared-ring async I/O interface, how it routes through standard KACS hooks, and the registry knobs for SQPOLL and URING_CMD.

Futexes on Peios — the userspace-fast-path kernel-fallback synchronisation primitive used by every modern threading library.

Smaller IPC primitives on Peios — kcmp for kernel object comparison, membarrier for cross-CPU memory barriers, and cross-memory-attach syscalls.