don't header-check the bhyve or viona API version

crates/bhyve-api/header-check/build.rs

@@ -24,6 +24,7 @@ fn ver_lt(ver: u32) -> bool {
     CHECK_VERSION.load(Ordering::Relaxed) < ver
 }
 /// Source checked against has API version equal to `ver` argument
+#[allow(dead_code)]
 fn ver_eq(ver: u32) -> bool {
     CHECK_VERSION.load(Ordering::Relaxed) == ver
 }
@@ -91,13 +92,15 @@ fn main() {
         // We expose our own copy for now for us as a constraint.
         "VM_MAXCPU" => true,
 
-        // Do not bother checking the version definition define if we are
-        // assuming the source is from a different version.
-        "VMM_CURRENT_INTERFACE_VERSION"
-            if !ver_eq(VMM_CURRENT_INTERFACE_VERSION) =>
-        {
-            true
-        }
+        // The bhyve interface is generally backwards-compatible; headers may be newer
+        // than Propolis knows about. In service of additive changes, ignore the
+        // interface version from headers.
+        //
+        // If items (structs, ioctl numbers) we know about changed, header-check
+        // will find and report those specifically. If items were removed, we
+        // may need to conditionally `skip_const` or `skip_field` based on the
+        // version Propolis knows about.
+        "VMM_CURRENT_INTERFACE_VERSION" => true,
 
         // API V11 saw the removal of several time-realted VMM_ARCH defines
         "VAI_TSC_BOOT_OFFSET" | "VAI_BOOT_HRTIME" | "VAI_TSC_FREQ"

crates/viona-api/header-check/Cargo.toml

@@ -13,6 +13,8 @@ libc = "0.2"
 [build-dependencies]
 cc = "1"
 ctest2 = "0.4.7"
+# Build-time conditions depend on the max API version defined in the crate
+viona_api = { path = ".." }
 
 [[test]]
 name = "main"

crates/viona-api/header-check/build.rs

@@ -7,6 +7,34 @@
 use std::convert::TryFrom;
 use std::env;
 use std::path::PathBuf;
+use std::str::FromStr;
+use std::sync::atomic::{AtomicU32, Ordering};
+
+use viona_api::VIONA_CURRENT_INTERFACE_VERSION;
+
+static CHECK_VERSION: AtomicU32 =
+    AtomicU32::new(VIONA_CURRENT_INTERFACE_VERSION);
+
+// A selection of helpers to concisely manage header-check rules, below.
+//
+// These are added in expectation of future use, hence `allow(dead_code)`.
+// Remove the attributes as they become used, please.
+
+/// Source checked against has API version greater than `ver` argument
+#[allow(dead_code)]
+fn ver_gt(ver: u32) -> bool {
+    CHECK_VERSION.load(Ordering::Relaxed) > ver
+}
+/// Source checked against has API version less than `ver` argument
+#[allow(dead_code)]
+fn ver_lt(ver: u32) -> bool {
+    CHECK_VERSION.load(Ordering::Relaxed) < ver
+}
+/// Source checked against has API version equal to `ver` argument
+#[allow(dead_code)]
+fn ver_eq(ver: u32) -> bool {
+    CHECK_VERSION.load(Ordering::Relaxed) == ver
+}
 
 fn main() {
     let mut cfg = ctest2::TestGenerator::new();
@@ -19,6 +47,27 @@ fn main() {
         }
     };
 
+    // Like with byhve: allow the user to specify a target interface version to
+    // check against.
+    match env::var("API_VERSION").ok().map(|v| u32::from_str(&v)) {
+        Some(Ok(ver)) => {
+            if ver > VIONA_CURRENT_INTERFACE_VERSION {
+                eprintln!(
+                    "API_VERSION {} cannot be > \
+                    VIONA_CURRENT_INTERFACE_VERSION ({})",
+                    ver, VIONA_CURRENT_INTERFACE_VERSION
+                );
+                std::process::exit(1);
+            }
+            CHECK_VERSION.store(ver, Ordering::Relaxed);
+        }
+        Some(Err(e)) => {
+            eprintln!("Invalid API_VERSION {:?}", e);
+            std::process::exit(1);
+        }
+        _ => {}
+    }
+
     let include_paths = ["usr/src/uts/intel", "usr/src/uts/common"];
     cfg.include("/usr/include");
     for p in include_paths {
@@ -31,6 +80,16 @@ fn main() {
     cfg.skip_const(move |name| match name {
         "VIONA_DEV_PATH" => true,
 
+        // Like bhyve, the viona interface is generally backwards-compatible.
+        // Headers may be newer than Propolis knows about. In service of
+        // additive changes, ignore the interface version from headers.
+        //
+        // If items (structs, ioctl numbers) we know about changed, header-check
+        // will find and report those specifically. If items were removed, we
+        // may need to conditionally `skip_const` or `skip_field` based on the
+        // version Propolis knows about.
+        "VIONA_CURRENT_INTERFACE_VERSION" => true,
+
         _ => false,
     });