internal/rosa: kernel headers

This is required by the toolchain and many other programs.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/kernel.go

@@ -0,0 +1,41 @@
+package rosa
+
+import (
+	"slices"
+
+	"hakurei.app/internal/pkg"
+)
+
+// newKernel is a helper for interacting with Kbuild.
+func (t Toolchain) newKernel(
+	script string,
+	extra ...pkg.Artifact,
+) pkg.Artifact {
+	const (
+		version  = "6.18.5"
+		checksum = "-V1e1WWl7HuePkmm84sSKF7nLuHfUs494uNMzMqXEyxcNE_PUE0FICL0oGWn44mM"
+	)
+	return t.New("kernel-"+version, slices.Concat([]pkg.Artifact{
+		t.NewMake(),
+	}, extra), nil, nil, `
+export LLVM=1
+export HOSTCFLAGS="${ROSA_CFLAGS}"
+export HOSTLDFLAGS="${LDFLAGS}"
+chmod -R +w /usr/src/linux && cd /usr/src/linux
+`+script, pkg.Path(AbsUsrSrc.Append("linux"), true, pkg.NewHTTPGetTar(
+		nil,
+		"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/"+
+			"snapshot/linux-"+version+".tar.gz",
+		mustDecode(checksum),
+		pkg.TarGzip,
+	)))
+}
+
+// NewKernelHeaders returns a [pkg.Artifact] containing kernel headers.
+func (t Toolchain) NewKernelHeaders() pkg.Artifact {
+	return t.newKernel(`
+make "-j$(nproc)" \
+	INSTALL_HDR_PATH=/work/system \
+	headers_install
+`, t.NewRsync())
+}