Updates to build on Windows

.gitattributes

@@ -0,0 +1 @@
+Dockerfile text eol=lf

internal/shim/task/service.go

@@ -167,6 +167,10 @@ func (s *service) shutdown(ctx context.Context) error {
 		}
 	}
 
+	// Remove the rootfs directory on Windows so containerd's bundle cleanup
+	// doesn't attempt a bind filter unmount (no-op on other platforms).
+	removeRootfsDir(ctx)
+
 	// Signal last event and stop forwarding
 	s.events <- nil
 

internal/shim/task/service_other.go

@@ -0,0 +1,25 @@
+//go:build !windows
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package task
+
+import "context"
+
+// removeRootfsDir is a no-op on non-Windows platforms. The bind-filter
+// unmount issue that necessitates rootfs removal only affects Windows.
+func removeRootfsDir(_ context.Context) {}

internal/shim/task/service_windows.go

@@ -0,0 +1,38 @@
+//go:build windows
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package task
+
+import (
+	"context"
+	"os"
+
+	"github.com/containerd/log"
+)
+
+// removeRootfsDir removes the rootfs directory from the bundle so that
+// containerd's bundle cleanup doesn't attempt a bind filter unmount.
+// On Windows, Unmount calls bindfilter.RemoveFileBinding which fails with
+// ERROR_ACCESS_DENIED on directories that were never bind filter mounts
+// (nerdbox uses VM-based virtio block devices instead). Removing the
+// directory makes UnmountAll a no-op.
+func removeRootfsDir(ctx context.Context) {
+	if err := os.RemoveAll("rootfs"); err != nil {
+		log.G(ctx).WithError(err).Warn("failed to remove rootfs directory during shutdown")
+	}
+}

internal/vm/libkrun/instance.go

@@ -72,10 +72,11 @@ func (*vmManager) NewInstance(ctx context.Context, state string) (vm.Instance, e
 	if runtime.GOOS != "windows" && len(p2) == 0 {
 		p2 = []string{"/usr/local/lib", "/usr/local/lib64", "/usr/lib", "/lib"}
 	}
-	sharedNames := []string{"libkrun.so"}
+	arch := kernelArch()
+	sharedNames := []string{fmt.Sprintf("libkrun-%s.so", arch), "libkrun.so"}
 	switch runtime.GOOS {
 	case "darwin":
-		sharedNames = []string{"libkrun.dylib", "libkrun-efi.dylib"}
+		sharedNames = []string{fmt.Sprintf("libkrun-%s.dylib", arch), "libkrun.dylib", fmt.Sprintf("libkrun-efi-%s.dylib", arch), "libkrun-efi.dylib"}
 		p2 = append(p2, "/opt/homebrew/lib")
 	case "windows":
 		sharedNames = []string{"krun.dll"}
@@ -103,9 +104,12 @@ func (*vmManager) NewInstance(ctx context.Context, state string) (vm.Instance, e
 			}
 		}
 		if initrdPath == "" {
-			path = filepath.Join(dir, "nerdbox-initrd")
-			if _, err := os.Stat(path); err == nil {
-				initrdPath = path
+			for _, name := range []string{fmt.Sprintf("nerdbox-initrd-%s", arch), "nerdbox-initrd"} {
+				path = filepath.Join(dir, name)
+				if _, err := os.Stat(path); err == nil {
+					initrdPath = path
+					break
+				}
 			}
 		}
 	}
@@ -116,7 +120,7 @@ func (*vmManager) NewInstance(ctx context.Context, state string) (vm.Instance, e
 		return nil, fmt.Errorf("nerdbox-kernel not found in PATH or LIBKRUN_PATH")
 	}
 	if initrdPath == "" {
-		return nil, fmt.Errorf("nerdbox-initrd not found in PATH or LIBKRUN_PATH")
+		return nil, fmt.Errorf("nerdbox-initrd-%s or nerdbox-initrd not found in PATH or LIBKRUN_PATH", arch)
 	}
 
 	lib, handler, err := openLibkrun(krunPath)
@@ -433,6 +437,16 @@ func (v *vmInstance) Shutdown(ctx context.Context) error {
 	if v.handler == 0 {
 		return fmt.Errorf("libkrun already closed")
 	}
+	// Stop the VM and wait for all threads (vCPU, virtio workers) to exit
+	// before unloading the library. krun_free_ctx is synchronous: it joins
+	// all threads and closes all file handles. Without this, dlClose rips
+	// the code out from under running threads and leaves file handles open,
+	// preventing containerd from cleaning up the bundle directory.
+	if v.vmc != nil {
+		if err := v.vmc.Shutdown(); err != nil {
+			log.G(ctx).WithError(err).Warn("krun_free_ctx failed during shutdown")
+		}
+	}
 	err := dlClose(v.handler)
 	if err != nil {
 		return err

pkg/shim/manager/manager_windows.go

@@ -124,7 +124,7 @@ func (manager) Start(ctx context.Context, bparams *bootapi.BootstrapParams) (_ *
 	// make sure to wait after start
 	go cmd.Wait()
 
-	if err = shim.WritePidFile("shim.pid", cmd.Process.Pid); err != nil {
+	if err = shim.WritePidFile(filepath.Join(bundlePath(ctx), "shim.pid"), cmd.Process.Pid); err != nil {
 		return nil, err
 	}
 
@@ -157,9 +157,38 @@ func (manager) Start(ctx context.Context, bparams *bootapi.BootstrapParams) (_ *
 	}, nil
 }
 
+// bundlePath extracts the bundle path from the context. The shim framework
+// stores it as shim.Opts{BundlePath: ...} via the -bundle flag.
+func bundlePath(ctx context.Context) string {
+	if o, ok := ctx.Value(shim.OptsKey{}).(shim.Opts); ok {
+		return o.BundlePath
+	}
+	return ""
+}
+
+// removeRootfs removes the rootfs directory from the bundle so that
+// containerd's bundle cleanup doesn't attempt a bind filter unmount.
+// On Windows, Unmount calls bindfilter.RemoveFileBinding which fails with
+// ERROR_ACCESS_DENIED on directories that were never bind filter mounts
+// (nerdbox uses VM-based virtio block devices instead). Removing the
+// directory makes UnmountAll a no-op.
+func removeRootfs(ctx context.Context) {
+	if bp := bundlePath(ctx); bp != "" {
+		os.RemoveAll(filepath.Join(bp, "rootfs"))
+	}
+}
+
 func (manager) Stop(ctx context.Context, id string) (shim.StopStatus, error) {
-	p, err := os.ReadFile("shim.pid")
+	p, err := os.ReadFile(filepath.Join(bundlePath(ctx), "shim.pid"))
 	if err != nil {
+		if os.IsNotExist(err) {
+			// The shim already exited and cleaned up its pid file.
+			removeRootfs(ctx)
+			return shim.StopStatus{
+				ExitedAt:   time.Now(),
+				ExitStatus: 128 + 9,
+			}, nil
+		}
 		return shim.StopStatus{}, err
 	}
 	pid, err := strconv.Atoi(strings.TrimSpace(string(p)))
@@ -203,6 +232,8 @@ func (manager) Stop(ctx context.Context, id string) (shim.StopStatus, error) {
 		return shim.StopStatus{}, fmt.Errorf("wait for shim process: %w", err)
 	}
 
+	removeRootfs(ctx)
+
 	return shim.StopStatus{
 		ExitedAt:   time.Now(),
 		ExitStatus: 128 + 9,