---
name: schos-cross-platform-build
description: "The build and tools support Windows, Linux, macOS and BSD; clang everywhere, and the four host assumptions that used to break"
metadata: 
  node_type: memory
  type: project
  originSessionId: 9d8a2aef-bcf0-47a0-96c6-f706efab4a95
  modified: 2026-08-09T12:26:54.787Z
---

**Nexoniarz develops from both Windows and Linux and switches between them**, so
nothing in the build may assume a host. As of 2026-08-09 all four are supported:
Windows (Git Bash/MSYS), Linux, macOS, and the BSDs. See
[[schunix-build-environment]] for why WSL is not an option on the Windows box.

**One toolchain, not two.** clang is a cross-compiler by construction, so a
single LLVM install produces every target the tree needs — bare-metal ELF, the
16/32-bit code below 1 MB, and Linux/musl userland — from any host. The Makefile
picks clang+lld whenever both are on PATH; `USE_GNU=1` forces the GNU fallback.
The old GNU branch had rotted: it passed `--no-warn-rwx-segments`, which is a
**hard error on lld**, and lld is the default linker on FreeBSD and macOS. It
also wanted a brewed `x86_64-elf-gcc` before a Mac could build at all.

**Host tools use the host's own `cc`.** Only mingw needs naming explicitly, and
only because clang defaults to an MSVC target there while `tools/mkfs.c` needs
`<unistd.h>` and `<dirent.h>`.

**The four things that were actually host-specific**, all fixed — worth
recognising the pattern before adding a fifth:

1. `<sys/sysmacros.h>` is glibc/musl only. macOS and the BSDs have no such
   header and take `major()`/`minor()` from `<sys/types.h>`. Guarded on
   `__linux__` now.
2. `sha256sum -c -` exists on Linux and Git Bash only. macOS has `shasum -a
   256`, FreeBSD/NetBSD `sha256`, OpenBSD `cksum -a sha256`. `tools/sha256check.sh`
   tries all five and compares digests itself rather than trusting a `-c` flag,
   whose input format also differs.
3. `nproc` is coreutils — absent on macOS and BSD, where it is
   `sysctl -n hw.ncpu`.
4. **`Join-Path $root 'build\x'` produces a filename containing a backslash on
   a Unix host.** PowerShell 7 runs on Linux/macOS/BSD, so the .ps1 tools are
   usable there, but only with forward slashes throughout and QEMU found on
   PATH instead of a hardcoded scoop location.

**Do not blanket-replace backslashes in the .ps1 tools.** `bootcheck.ps1` sends
`printf 'caf\303\251'` to the guest to test UTF-8; rewriting those octal escapes
changes what the test asserts without failing it. The sweep is restricted to
known directory prefixes for exactly this reason.

**Ports do not build on Windows** — `make ports` skips with a message and the
tree relies on `sysroot/` being pre-staged. Building musl/toybox/mksh from
source needs a Linux host. That is a real reason to keep the Linux path working,
not a theoretical one.

**Unverified, and say so when it matters:** the Linux, macOS and BSD paths are
written from documented behaviour and have **never been executed** — this
machine has no WSL and no second host. Windows is the only host where the build
and `tools/bootcheck.ps1` have actually been run green.