Unix Compatibility

Unix Compatibility

XAIOS is a freestanding Unix-like operating system with its own syscall and userspace ABI. FreeBSD is the primary external behavioral reference for portable command, SSH/SFTP and network work.

This does not mean that XAIOS is FreeBSD-derived or FreeBSD binary compatible. XAIOS also does not implement a Linux binary ABI. Passing a client gate establishes only the tested command or wire behavior.

Current Evidence

Client	Current QEMU evidence
FreeBSD 15.1 AArch64	Official checksum-pinned VM; OpenSSH public-key acceptance and rejection, xaiosctl, SFTP write/stat/read/rename/remove, interactive PTY ANSI htop, and UDP echo.
macOS	Native OpenSSH/SFTP administration and one-guest parallel load coverage.
Debian 13	Independent Linux/OpenSSH cross-client coverage for password policy, stateful shell prompts, interactive nano, recursive filesystem operations, command errors, rekey, administration, persistence, concurrency, interactive PTY htop and malformed network traffic.

The core command subset now includes ls, cd, pwd, mkdir, rm, cp, mv, cat, alternate-screen less, grep, find, ps, df, du, tar, zip, unzip, outbound ssh, and recursive scp. POSIX ustar/PAX, GNU long-name tar, gzip-wrapped tar, stored/Deflate ZIP and Unix/Windows ZIP origin metadata are validated within MutableFS limits. XAIOS-created archives pass macOS and Debian readers. Recursive SFTP-backed scp passes in both directions against Debian OpenSSH.

This is a documented portable subset, not a complete FreeBSD base system. See the repository document below for exact options, limits, unsupported archive features, and outbound SSH authentication constraints.

Run the FreeBSD reference gate with:

make qemu-freebsd-network-suite
make qemu-freebsd-bidirectional-suite

The first run downloads the official compressed FreeBSD image into ~/.cache/xaios/freebsd. Both the compressed archive and decompressed image are SHA-256 checked. Tests use a disposable overlay; the cached vendor image is not modified.

The bidirectional gate additionally places the real FreeBSD VM inside a Dockerized QEMU harness, starts base-system sshd, and validates XAIOS's password-authenticated outbound SSH and recursive SFTP-backed SCP client in both transfer directions. Docker supplies process isolation and repeatable QEMU dependencies; it does not substitute a Linux kernel for FreeBSD. See the network interoperability summary for the complete local and Intel VPS contract.

See the authoritative repository document: Unix compatibility boundary.