Update build to run qemu on MacOS

This commit is contained in:
Daniel Samson
2026-07-03 16:43:00 +01:00
parent 31bf86af56
commit 50f3610768
3 changed files with 76 additions and 10 deletions
+6 -4
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@@ -13,11 +13,13 @@ kernel heap. See [`docs/`](docs/README.md) for how each piece works.
versions are rejected, because Zig makes breaking changes between releases
pre-1.0. A toolchain manager such as [zvm](https://github.com/tristanisham/zvm)
or `zigup` will pick up `.zig-version` automatically.
- **QEMU** (`qemu-system-x86_64`) — to run and test the kernel.
- **QEMU** (`qemu-system-x86_64`) — to run and test the kernel. On macOS,
`brew install qemu` also bundles the OVMF firmware below.
- **OVMF** UEFI firmware — the `edk2-ovmf` package (Arch), `ovmf` (Debian/Ubuntu),
or `edk2-ovmf` (Fedora). The build defaults to the Arch paths
(`/usr/share/edk2/x64/OVMF_{CODE,VARS}.4m.fd`); override with `-Dovmf-code=` and
`-Dovmf-vars=` if your distro installs them elsewhere.
or `edk2-ovmf` (Fedora); on macOS it ships inside the Homebrew `qemu` formula.
Both the build and the test harness probe the known Arch/Debian/Fedora/macOS
layouts and use the first that exists, so no configuration is normally needed.
Override with `-Dovmf-code=` / `-Dovmf-vars=` (build) if yours lives elsewhere.
- **Python 3** — for the QEMU integration test harness.
## Build
+31 -4
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@@ -16,6 +16,18 @@ fn ensureZigVersion() void {
}
}
/// Return the first path in `candidates` that exists on the build host, else the
/// first candidate as a fallback so a missing-firmware error still names a
/// concrete (and, by convention, the primary) path. Used to locate OVMF firmware
/// across distro/OS layouts without configuration.
fn firstExisting(io: std.Io, candidates: []const []const u8) []const u8 {
for (candidates) |path| {
std.Io.Dir.accessAbsolute(io, path, .{}) catch continue;
return path;
}
return candidates[0];
}
pub fn build(b: *std.Build) void {
ensureZigVersion();
@@ -105,18 +117,33 @@ pub fn build(b: *std.Build) void {
b.installArtifact(efiexe);
// --- run-efi: boot BOOTX64.efi in QEMU with OVMF firmware ---
// OVMF paths follow the Arch (edk2-ovmf) layout; override with -Dovmf-code
// and -Dovmf-vars if your distro installs them elsewhere.
// Firmware lives in different places per OS/distro, so probe the known
// layouts (Arch, Debian/Ubuntu, Fedora, macOS Homebrew) and use the first
// that exists. Override with -Dovmf-code / -Dovmf-vars if yours is elsewhere.
const ovmf_code = b.option(
[]const u8,
"ovmf-code",
"Path to the OVMF_CODE firmware image",
) orelse "/usr/share/edk2/x64/OVMF_CODE.4m.fd";
) orelse firstExisting(b.graph.io, &.{
"/usr/share/edk2/x64/OVMF_CODE.4m.fd", // Arch
"/usr/share/OVMF/OVMF_CODE_4M.fd", // Debian/Ubuntu
"/usr/share/OVMF/OVMF_CODE.fd", // older Debian/Ubuntu
"/usr/share/edk2-ovmf/x64/OVMF_CODE.fd", // Fedora
"/opt/homebrew/share/qemu/edk2-x86_64-code.fd", // macOS Homebrew (Apple Silicon)
"/usr/local/share/qemu/edk2-x86_64-code.fd", // macOS Homebrew (Intel)
});
const ovmf_vars = b.option(
[]const u8,
"ovmf-vars",
"Path to the OVMF_VARS firmware image (a writable copy is made)",
) orelse "/usr/share/edk2/x64/OVMF_VARS.4m.fd";
) orelse firstExisting(b.graph.io, &.{
"/usr/share/edk2/x64/OVMF_VARS.4m.fd", // Arch
"/usr/share/OVMF/OVMF_VARS_4M.fd", // Debian/Ubuntu
"/usr/share/OVMF/OVMF_VARS.fd", // older Debian/Ubuntu
"/usr/share/edk2-ovmf/x64/OVMF_VARS.fd", // Fedora
"/opt/homebrew/share/qemu/edk2-i386-vars.fd", // macOS Homebrew (Apple Silicon)
"/usr/local/share/qemu/edk2-i386-vars.fd", // macOS Homebrew (Intel)
});
// Assemble an EFI System Partition layout: esp/EFI/BOOT/BOOTX64.efi
const efi_install = b.addInstallArtifact(efiexe, .{
+39 -2
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@@ -35,8 +35,26 @@ ARCHES = {
"x86_64": {
"zig_flags": [], # build.zig currently pins the kernel to x86_64
"qemu": "qemu-system-x86_64",
"ovmf_code": "/usr/share/edk2/x64/OVMF_CODE.4m.fd",
"ovmf_vars": "/usr/share/edk2/x64/OVMF_VARS.4m.fd",
# Firmware lives in different places per OS/distro; resolve_firmware()
# picks the first that exists so the harness runs unconfigured on Arch,
# Debian/Ubuntu, Fedora, and macOS (Homebrew). Override by reordering or
# dropping an absolute path at the front.
"ovmf_code": [
"/usr/share/edk2/x64/OVMF_CODE.4m.fd", # Arch
"/usr/share/OVMF/OVMF_CODE_4M.fd", # Debian/Ubuntu
"/usr/share/OVMF/OVMF_CODE.fd", # older Debian/Ubuntu
"/usr/share/edk2-ovmf/x64/OVMF_CODE.fd", # Fedora
"/opt/homebrew/share/qemu/edk2-x86_64-code.fd", # macOS Homebrew (Apple Silicon)
"/usr/local/share/qemu/edk2-x86_64-code.fd", # macOS Homebrew (Intel)
],
"ovmf_vars": [
"/usr/share/edk2/x64/OVMF_VARS.4m.fd", # Arch
"/usr/share/OVMF/OVMF_VARS_4M.fd", # Debian/Ubuntu
"/usr/share/OVMF/OVMF_VARS.fd", # older Debian/Ubuntu
"/usr/share/edk2-ovmf/x64/OVMF_VARS.fd", # Fedora
"/opt/homebrew/share/qemu/edk2-i386-vars.fd", # macOS Homebrew (Apple Silicon)
"/usr/local/share/qemu/edk2-i386-vars.fd", # macOS Homebrew (Intel)
],
"efi_app": ("EFI/BOOT/BOOTX64.efi", "BOOTX64.efi"), # (dest in ESP, name in zig-out/bin)
"kernel": ("danos", "danos"),
# Built as a function so we can splice in per-run paths.
@@ -123,6 +141,24 @@ def make_esp(arch):
return esp
def resolve_firmware(arch):
"""Collapse the ovmf_code/ovmf_vars candidate lists to the first path that
exists on this machine. Mutates `arch` in place; idempotent (a resolved
string is left untouched). Exits with a clear message if none is found."""
for key, label in (("ovmf_code", "OVMF_CODE"), ("ovmf_vars", "OVMF_VARS")):
val = arch[key]
if isinstance(val, str):
continue # already resolved on a previous call
for cand in val:
if os.path.exists(cand):
arch[key] = cand
break
else:
sys.exit(f"error: no {label} firmware image found; looked in:\n "
+ "\n ".join(val)
+ "\nInstall OVMF (edk2-ovmf / ovmf) or add its path above.")
def run_case(arch, case):
err = build(arch, case["name"])
if err:
@@ -176,6 +212,7 @@ def main():
if not shutil.which(arch["qemu"]):
print(f"error: {arch['qemu']} not found on PATH", file=sys.stderr)
return 2
resolve_firmware(arch)
selected = [c for c in CASES if not args.cases or c["name"] in args.cases]
os.makedirs(WORK, exist_ok=True)