Fix CDI spec generation to respect driver root for Tegra CSV files

elezar · claude · elezar · commit f27fd1439556 · 2026-04-15T10:40:00.000+02:00
On Tegra-based systems the nvcdi library resolves CSV mount specs from
/etc/nvidia-container-runtime/host-files-for-container.d using hardcoded
absolute paths, ignoring the configured driver root. When the device
plugin runs in a container with the host filesystem mounted at a
non-default driver root the CSV files are unreachable at their absolute
paths, causing CDI spec generation to fail.

Inject driver-root-aware CSV file paths via nvcdi.WithCSVFiles() when
the platform is detected as Tegra. The helper csvFilesForRoot() checks
for the CSV directory under the driver root first, falling back to the
absolute path, and returns nil (letting nvcdi use its own defaults) if
neither location exists.

Also extend the NVML guard so that pure iGPU Tegra systems without NVML
are not incorrectly reduced to a null CDI handler.

Co-Authored-By: Claude Sonnet 4.6 &lt;noreply@anthropic.com&gt;
Signed-off-by: Evan Lezar &lt;elezar@nvidia.com&gt;
diff --git a/internal/cdi/cdi.go b/internal/cdi/cdi.go
@@ -18,6 +18,7 @@ package cdi
 
 import (
 	"fmt"
+	"os"
 	"path/filepath"
 	"strings"
 
@@ -87,7 +88,8 @@ func New(infolib info.Interface, nvmllib nvml.Interface, devicelib device.Interf
 		return &null{}, nil
 	}
 	hasNVML, _ := infolib.HasNvml()
-	if !hasNVML {
+	platform := infolib.ResolvePlatform()
+	if !hasNVML && platform != info.PlatformTegra {
 		klog.Warning("No valid resources detected, creating a null CDI handler")
 		return &null{}, nil
 	}
@@ -128,6 +130,13 @@ func New(infolib info.Interface, nvmllib nvml.Interface, devicelib device.Interf
 		nvcdi.WithVendor(c.vendor),
 	}
 
+	// On Tegra (CSV mode), the default CSV files live under the driver root.
+	// Inject driver-root-aware paths explicitly so the nvcdi library does not
+	// fall back to the hardcoded absolute paths returned by csv.DefaultFileList().
+	if platform == info.PlatformTegra {
+		commonOptions = append(commonOptions, nvcdi.WithCSVFiles(csvFilesForRoot(c.driverRoot)))
+	}
+
 	c.cdilibs = make(map[string]nvcdi.SpecGenerator)
 
 	c.cdilibs["gpu"], err = nvcdi.New(
@@ -177,16 +186,6 @@ func (cdi *cdiHandler) CreateSpecFile() error {
 	for class, cdilib := range cdi.cdilibs {
 		cdi.logger.Infof("Generating CDI spec for resource: %s/%s", cdi.vendor, class)
 
-		if class == "gpu" {
-			ret := cdi.nvmllib.Init()
-			if ret != nvml.SUCCESS {
-				return fmt.Errorf("failed to initialize NVML: %v", ret)
-			}
-			defer func() {
-				_ = cdi.nvmllib.Shutdown()
-			}()
-		}
-
 		spec, err := cdilib.GetSpec()
 		if err != nil {
 			return fmt.Errorf("failed to get CDI spec: %v", err)
@@ -268,3 +267,33 @@ func (cdi *cdiHandler) AdditionalDevices() []string {
 	}
 	return devices
 }
+
+// defaultCSVMountSpecPath mirrors the constant defined in the nvidia-container-toolkit's
+// internal/platform-support/tegra/csv package.
+const defaultCSVMountSpecPath = "/etc/nvidia-container-runtime/host-files-for-container.d"
+
+var defaultCSVFileNames = []string{"devices.csv", "drivers.csv", "l4t.csv"}
+
+// csvFilesForRoot returns the Tegra CSV file paths to use for CDI spec generation.
+// It checks for the CSV directory at the driver root first, then falls back to the
+// absolute path. Returns nil if the directory is not found at either location,
+// allowing nvcdi to fall back to csv.DefaultFileList().
+func csvFilesForRoot(driverRoot string) []string {
+	roots := []string{driverRoot}
+	if driverRoot != "/" {
+		roots = append(roots, "/")
+	}
+	for _, root := range roots {
+		csvDir := filepath.Join(root, defaultCSVMountSpecPath)
+		stat, err := os.Stat(csvDir)
+		if err != nil || !stat.IsDir() {
+			continue
+		}
+		paths := make([]string, len(defaultCSVFileNames))
+		for i, f := range defaultCSVFileNames {
+			paths[i] = filepath.Join(csvDir, f)
+		}
+		return paths
+	}
+	return nil
+}
diff --git a/internal/cdi/csv_test.go b/internal/cdi/csv_test.go
@@ -0,0 +1,68 @@
+/**
+# Copyright (c) NVIDIA CORPORATION.  All rights reserved.
+#
+# 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 cdi
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCSVFilesForRoot(t *testing.T) {
+	testCases := []struct {
+		description   string
+		setup         func(t *testing.T) string // returns driverRoot
+		expectedPaths func(driverRoot string) []string
+	}{
+		{
+			description: "directory exists at driver root",
+			setup: func(t *testing.T) string {
+				root := t.TempDir()
+				csvDir := filepath.Join(root, defaultCSVMountSpecPath)
+				require.NoError(t, os.MkdirAll(csvDir, 0755))
+				return root
+			},
+			expectedPaths: func(driverRoot string) []string {
+				csvDir := filepath.Join(driverRoot, defaultCSVMountSpecPath)
+				return []string{
+					filepath.Join(csvDir, "devices.csv"),
+					filepath.Join(csvDir, "drivers.csv"),
+					filepath.Join(csvDir, "l4t.csv"),
+				}
+			},
+		},
+		{
+			description: "directory does not exist at driver root or absolute path",
+			setup: func(t *testing.T) string {
+				return t.TempDir()
+			},
+			expectedPaths: func(_ string) []string {
+				return nil
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			driverRoot := tc.setup(t)
+			got := csvFilesForRoot(driverRoot)
+			require.Equal(t, tc.expectedPaths(driverRoot), got)
+		})
+	}
+}
