Merge pull request #4932 from tianon/arm64-fallback

Allow arm64 to fallback to arm (v8, v7, v6, v5)

platforms/compare.go

@@ -57,6 +57,18 @@ func platformVector(platform specs.Platform) []specs.Platform {
 				})
 			}
 		}
+	case "arm64":
+		variant := platform.Variant
+		if variant == "" {
+			variant = "v8"
+		}
+		vector = append(vector, platformVector(specs.Platform{
+			Architecture: "arm",
+			OS:           platform.OS,
+			OSVersion:    platform.OSVersion,
+			OSFeatures:   platform.OSFeatures,
+			Variant:      variant,
+		})...)
 	}
 
 	return vector

platforms/compare_test.go

@@ -166,17 +166,17 @@ func TestOnly(t *testing.T) {
 			platform: "linux/arm64",
 			matches: map[bool][]string{
 				true: {
+					"linux/arm",
+					"linux/arm/v5",
+					"linux/arm/v6",
+					"linux/arm/v7",
+					"linux/arm/v8",
 					"linux/arm64",
 					"linux/arm64/v8",
 				},
 				false: {
 					"linux/amd64",
-					"linux/arm",
 					"linux/arm/v4",
-					"linux/arm/v5",
-					"linux/arm/v6",
-					"linux/arm/v7",
-					"linux/arm/v8",
 					"linux/arm/v9",
 					"linux/arm64/v9",
 					"windows/amd64",

platforms/cpuinfo.go

@@ -107,12 +107,7 @@ func getCPUVariant() string {
 
 	switch strings.ToLower(variant) {
 	case "8", "aarch64":
-		// special case: if running a 32-bit userspace on aarch64, the variant should be "v7"
-		if runtime.GOARCH == "arm" {
-			variant = "v7"
-		} else {
-			variant = "v8"
-		}
+		variant = "v8"
 	case "7", "7m", "?(12)", "?(13)", "?(14)", "?(15)", "?(16)", "?(17)":
 		variant = "v7"
 	case "6", "6tej":