add build script so zig build works (sort of) as expected

.config.helloworld_qemu-x86_64

@@ -1,8 +1,8 @@
 #
 # Automatically generated file; DO NOT EDIT.
-# Unikraft/0.17.0~8838cfd Configuration
+# Unikraft/0.17.0~e7be641 Configuration
 #
-CONFIG_UK_FULLVERSION="0.17.0~8838cfd"
+CONFIG_UK_FULLVERSION="0.17.0~e7be641"
 CONFIG_UK_CODENAME="Calypso"
 CONFIG_UK_ARCH="x86_64"
 CONFIG_HOST_ARCH="x86_64"

Makefile.uk

@@ -2,4 +2,5 @@ $(eval $(call addlib,apphelloworld))
 
 APPHELLOWORLD_SRCS-y += $(APPHELLOWORLD_BASE)/helloworld.c
 APPHELLOWORLD_SRCS-y += $(APPHELLOWORLD_BASE)/undefined.c
-UK_ALIBS-y += $(APPHELLOWORLD_BASE)/libziggy.a
+UK_ALIBS-y += ${LIB_ZIGGY}
+#UK_ALIBS-y += $(APPHELLOWORLD_BASE)/ziggy/zig-out/lib/libziggy.a

README.md

@@ -1,14 +1,29 @@
 Native Unikraft Microkernel Build for Zig libraries
 ===================================================
 
-This is an example repository, due to be cleaned up. For now, install Kraftkit
+
-and zig and build it this way:
+Building
+--------
+
+Everything assumes Linux on x86_64, though some trivial changes should allow
+aarch64. Install the following:
+
+* [Zig](https://ziglang.org). Versions 0.12.0 and 0.13.0 should work
+* [QEMU](https://www.qemu.org/download/#linux)
+* [Kraftkit](https://unikraft.org/docs/cli/install)
+
+Then run `zig build run` and everything will compile and run. The zig source
+code is all in the `ziggy` directory
+
+
+
+Notes
+-----
+
+The build script basically runs these commands:
 
 ```sh
-(cd ziggy && zig build -Doptimize=ReleaseSafe -Dtarget=x86_64-linux-gnu.2.13 -Dcpu=baseline) && cp ziggy/zig-out/lib/libziggy.a . &&  kraft build --plat qemu --arch x86_64 --log-level debug --log-type basic && kraft run --plat qemu --arch x86_64
+(cd ziggy && zig build)
+LIBZIGGY=$(pwd)/ziggy/zig-out/lib/libziggy.a kraft build --plat qemu --arch x86_64 --log-level debug --log-type basic
+kraft run --plat qemu --arch x86_64
 ```
-
-Only works on Linux, with QEMU (install that too!) and Zig 0.13.0 (though probably
-works on 0.12.0 as well).
-
-More to follow

build.zig

@@ -0,0 +1,137 @@
+const std = @import("std");
+
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
+pub fn build(b: *std.Build) void {
+    // Standard target options allows the person running `zig build` to choose
+    // what target to build for. Here we do not override the defaults, which
+    // means any target is allowed, and the default is native. Other options
+    // for restricting supported target set are available.
+    const target = b.standardTargetOptions(.{});
+
+    // Standard optimization options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
+    // set a preferred release mode, allowing the user to decide how to optimize.
+    const optimize = b.standardOptimizeOption(.{});
+
+    const ziggy = b.dependency("ziggy", .{
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const install_step = b.getInstallStep();
+    const build_cmd = b.addSystemCommand(&[_][]const u8{
+        "kraft",
+        "build",
+        "--plat",
+        "qemu",
+        "--arch",
+        "x86_64",
+        "--log-level",
+        "debug",
+        // "--log-type",
+        // "basic",
+    });
+    install_step.dependOn(&build_cmd.step);
+
+    const artifact_env_var = LazyPathEnvironmentVariable.create(
+        b,
+        "LIB_ZIGGY",
+        ziggy.artifact("libziggy").getEmittedBin(),
+        build_cmd,
+    );
+    artifact_env_var.step.dependOn(&ziggy.artifact("libziggy").step);
+
+    build_cmd.step.dependOn(&artifact_env_var.step);
+    // This *creates* a Run step in the build graph, to be executed when another
+    // step is evaluated that depends on it. The next line below will establish
+    // such a dependency.
+    const run_cmd = b.addSystemCommand(&[_][]const u8{
+        "kraft",
+        "run",
+        "--plat",
+        "qemu",
+        "--arch",
+        "x86_64",
+    });
+
+    // By making the run step depend on the install step, it will be run from the
+    // installation directory rather than directly from within the cache directory.
+    // This is not necessary, however, if the application depends on other installed
+    // files, this ensures they will be present and in the expected location.
+    run_cmd.step.dependOn(install_step);
+
+    // This allows the user to pass arguments to the application in the build
+    // command itself, like this: `zig build run -- arg1 arg2 etc`
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    // This creates a build step. It will be visible in the `zig build --help` menu,
+    // and can be selected like this: `zig build run`
+    // This will evaluate the `run` step rather than the default, which is "install".
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+
+    const kraft_clean_cmd = b.addSystemCommand(&[_][]const u8{
+        "kraft",
+        "clean",
+        "--plat",
+        "qemu",
+        "--arch",
+        "x86_64",
+    });
+    const clean_step = b.step("clean", "Clean the unikraft build");
+    clean_step.dependOn(&kraft_clean_cmd.step);
+
+    const distclean_cmd = b.addSystemCommand(&[_][]const u8{
+        "rm",
+        "-rf",
+        ".unikraft",
+    });
+    const distclean_step = b.step("distclean", "Deep clean the unikraft build");
+    distclean_step.dependOn(clean_step);
+    distclean_step.dependOn(&distclean_cmd.step);
+}
+
+const LazyPathEnvironmentVariable = struct {
+    const base_id: std.Build.Step.Id = .custom;
+
+    step: std.Build.Step,
+
+    lazy_path: std.Build.LazyPath,
+
+    key: []const u8,
+
+    run_step: *std.Build.Step.Run,
+
+    pub fn create(
+        owner: *std.Build,
+        comptime key: []const u8,
+        lazy_path: std.Build.LazyPath,
+        run_step: *std.Build.Step.Run,
+    ) *LazyPathEnvironmentVariable {
+        const step = owner.allocator.create(LazyPathEnvironmentVariable) catch @panic("OOM");
+        step.* = .{
+            .step = std.Build.Step.init(.{
+                .id = base_id,
+                .name = "env var " ++ key,
+                .owner = owner,
+                .makeFn = make,
+            }),
+            .key = key,
+            .lazy_path = lazy_path,
+            .run_step = run_step,
+        };
+        return step;
+    }
+
+    fn make(step: *std.Build.Step, prog_node: std.Progress.Node) error{ MakeFailed, MakeSkipped }!void {
+        _ = prog_node;
+        const b = step.owner;
+        // const arena = b.allocator;
+        const this: *LazyPathEnvironmentVariable = @fieldParentPtr("step", step);
+        this.run_step.setEnvironmentVariable(this.key, this.lazy_path.getPath2(b, &this.step));
+    }
+};

build.zig.zon

@@ -0,0 +1,38 @@
+.{
+    // This is the default name used by packages depending on this one. For
+    // example, when a user runs `zig fetch --save <url>`, this field is used
+    // as the key in the `dependencies` table. Although the user can choose a
+    // different name, most users will stick with this provided value.
+    //
+    // It is redundant to include "zig" in this name because it is already
+    // within the Zig package namespace.
+    .name = "unikraft-zig-native-hello",
+
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.0.0",
+
+    // This field is optional.
+    // This is currently advisory only; Zig does not yet do anything
+    // with this value.
+    //.minimum_zig_version = "0.11.0",
+
+    // This field is optional.
+    // Each dependency must either provide a `url` and `hash`, or a `path`.
+    // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+    // Once all dependencies are fetched, `zig build` no longer requires
+    // internet connectivity.
+    .dependencies = .{
+        .ziggy = .{
+            .path = "ziggy",
+        },
+    },
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "ziggy",
+        // For example...
+        //"LICENSE",
+        //"README.md",
+    },
+}

ziggy/build.zig

@@ -16,7 +16,7 @@ pub fn build(b: *std.Build) void {
     const optimize = b.standardOptimizeOption(.{});
 
     const lib = b.addStaticLibrary(.{
-        .name = "ziggy",
+        .name = "libziggy",
         // In this case the main source file is merely a path, however, in more
         // complicated build scripts, this could be a generated file.
         .root_source_file = b.path("src/root.zig"),

ziggy/src/root.zig

@@ -9,6 +9,10 @@ export fn add(a: i32, b: i32) i32 {
         const out = std.io.getStdErr().writer();
         out.print("WARNING: Building debug mode will likely crash in Unikraft environment. Use -Doptimize=ReleaseSafe\n", .{}) catch {};
     }
+    if (builtin.mode != .Debug) {
+        const out = std.io.getStdOut().writer();
+        out.print("info: Built with a release build\n", .{}) catch {};
+    }
     const out = std.io.getStdOut().writer();
     out.print("Hello from lib\n", .{}) catch {};
     std.log.err("logging error", .{});