Update build to run qemu on MacOS

test/qemu_test.py

@@ -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)