Enable riscv64 for most samples.

audio-echo/app/src/main/cpp/CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.22.1)
 project(echo LANGUAGES C CXX)
 
 add_library(echo
-  SHARED
+    SHARED
     audio_main.cpp
     audio_player.cpp
     audio_recorder.cpp
@@ -12,12 +12,28 @@ add_library(echo
 
 #include libraries needed for echo lib
 target_link_libraries(echo
-  PRIVATE
+    PRIVATE
     OpenSLES
     android
     log
     atomic)
 
 target_compile_options(echo
-  PRIVATE
-    -Wall -Werror)
+    PRIVATE
+    -Wall
+    -Werror
+)
+
+if (ANDROID_ABI STREQUAL riscv64)
+    # This sample uses OpenSLES, which was deprecated in API 26. Our
+    # minSdkVersion is 21, but we also build for riscv64, which isn't a
+    # supported ABI yet and so that configuration is built for the latest API
+    # level supported by the NDK.
+    #
+    # Longer term, this sample should probably be deleted. App developers
+    # should be using Oboe rather than OpenSLES, and we already have a separate
+    # sample for Oboe. There is some potentially useful audio latency
+    # measurement in this sample that should be moved to the Oboe sample before
+    # we delete it though.
+    target_compile_options(echo PRIVATE -Wno-deprecated-declarations)
+endif ()

build-logic/src/main/java/com/android/ndk/samples/buildlogic/AndroidApplicationConventionPlugin.kt

@@ -32,6 +32,22 @@ class AndroidApplicationConventionPlugin : Plugin<Project> {
                             arguments.add("-DANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES=ON")
                         }
                     }
+
+                    ndk {
+                        // riscv64 isn't a supported Android ABI yet (August 2025), but we're
+                        // enabling it here as part of that experiment. Until it's a supported ABI,
+                        // don't include this in your app, as Play will block uploads of APKs which
+                        // contain riscv64 libraries.
+                        abiFilters.addAll(
+                            listOf(
+                                "arm64-v8a",
+                                "armeabi-v7a",
+                                "riscv64",
+                                "x86",
+                                "x86_64",
+                            )
+                        )
+                    }
                 }
                 compileOptions {
                     sourceCompatibility = Versions.JAVA

build-logic/src/main/java/com/android/ndk/samples/buildlogic/AndroidLibraryConventionPlugin.kt

@@ -35,6 +35,21 @@ class AndroidLibraryConventionPlugin : Plugin<Project> {
                             arguments.add("-DANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES=ON")
                         }
                     }
+                    ndk {
+                        // riscv64 isn't a supported Android ABI yet (August 2025), but we're
+                        // enabling it here as part of that experiment. Until it's a supported ABI,
+                        // don't include this in your app, as Play will block uploads of APKs which
+                        // contain riscv64 libraries.
+                        abiFilters.addAll(
+                            listOf(
+                                "arm64-v8a",
+                                "armeabi-v7a",
+                                "riscv64",
+                                "x86",
+                                "x86_64",
+                            )
+                        )
+                    }
                 }
                 compileOptions {
                     sourceCompatibility = Versions.JAVA

hello-libs/app/build.gradle

@@ -14,6 +14,12 @@ android {
                 arguments '-DANDROID_STL=c++_static'
             }
         }
+
+        ndk {
+            // This sample relies on prebuilt libraries, and we haven't built
+            // rv64 versions of those libraries yet.
+            abiFilters.remove("riscv64")
+        }
     }
 
     externalNativeBuild {

hello-neon/app/build.gradle

@@ -4,11 +4,23 @@ plugins {
 
 android {
     namespace 'com.example.helloneon'
-    
+
     defaultConfig {
         applicationId "com.example.helloneon"
         versionCode 1
         versionName "1.0"
+
+        ndk {
+            // rv64 doesn't support Neon intrinsics. You shouldn't really use
+            // those anyway, since they're just a non-portable wrapper around
+            // the portable Clang vector intrinsics:
+            //
+            // https://clang.llvm.org/docs/LanguageExtensions.html#vectors-and-extended-vectors
+            //
+            // TODO: Delete this sample in favor of a better one.
+            // https://github.com/android/ndk-samples/issues/1011
+            abiFilters.remove("riscv64")
+        }
     }
 
     externalNativeBuild {

hello-oboe/app/build.gradle

@@ -5,13 +5,18 @@ plugins {
 
 android {
     namespace 'com.google.example.hellooboe'
-    
+
     defaultConfig {
         applicationId "com.google.example.hellooboe"
         versionCode 1
         versionName "1.0"
         externalNativeBuild.cmake {
-            arguments  "-DANDROID_STL=c++_shared"
+            arguments "-DANDROID_STL=c++_shared"
+        }
+
+        ndk {
+            // Oboe doesn't currently (August 2025) include riscv64 libraries.
+            abiFilters.remove("riscv64")
         }
     }
 

hello-vulkan/app/build.gradle

@@ -21,7 +21,7 @@ plugins {
 
 android {
     namespace 'com.android.hellovk'
-    
+
     defaultConfig {
         applicationId 'com.android.hellovk'
         // TODO: Figure out why this isn't 24.
@@ -35,6 +35,11 @@ android {
         shaders {
             glslcArgs.addAll(['-c'])
         }
+        ndk {
+            // GameActivity doesn't currently (August 2025) include riscv64
+            // libraries.
+            abiFilters.remove("riscv64")
+        }
     }
 
     externalNativeBuild {

native-activity/app/src/main/cpp/CMakeLists.txt

@@ -41,3 +41,16 @@ target_link_libraries(native-activity
     EGL
     GLESv1_CM
     log)
+
+if (ANDROID_ABI STREQUAL riscv64)
+    # This sample uses Sensor Manager and Choreographer APIs which are
+    # deprecated in modern API levels. Our minSdkVersion is 21, but we also
+    # build for riscv64, which isn't a supported ABI yet and so that
+    # configuration is built for the latest API level supported by the NDK.
+    #
+    # This sample should be tweaked to use the replacement APIs when they're
+    # available at runtime and only use the older APIs on older devices. For
+    # now, just disable the deprecation warnings so we can get the riscv64
+    # samples building in CI, and we can come back to clean that up later.
+    target_compile_options(native-activity PRIVATE -Wno-deprecated-declarations)
+endif ()

prefab/curl-ssl/app/build.gradle

@@ -34,6 +34,12 @@ android {
                 }
             }
         }
+
+        ndk {
+            // None of the ndkports libraries currently (August 2025) include
+            // riscv64 libraries.
+            abiFilters.remove("riscv64")
+        }
     }
 
     externalNativeBuild {

prefab/prefab-dependency/app/build.gradle

@@ -34,6 +34,12 @@ android {
                 }
             }
         }
+
+        ndk {
+            // None of the ndkports libraries currently (August 2025) include
+            // riscv64 libraries.
+            abiFilters.remove("riscv64")
+        }
     }
 
     externalNativeBuild {

sanitizers/app/build.gradle

@@ -16,9 +16,59 @@ android {
         minSdk 21
         versionCode 1
         versionName "1.0"
+
+        // The sanitizers aren't all mutually compatible, so this sample is
+        // split into a buildType per sanitizer below. For most of those
+        // sanitizers, we support every ABI. The HWASan buildType is the
+        // exception, where we want to enable only arm64-v8a.
+        //
+        // Unfortunately, the convention plugin enables every ABI using
+        // defaultConfig.ndk.abiFilters, which apparently overrides anything we
+        // do in buildTypes. To be able to control which ABIs get built here
+        // using buildTypes, we have to undo the work done by the convention
+        // plugin by clearing the defaultConfig abiFilters. Instead, we enable
+        // all the ABIs in the debug and release buildTypes below, inherit from
+        // those for most of the sanitizers, but then again reset the list for
+        // HWASan to enable only arm64-v8a.
+        //
+        // We could instead change the convention plugin to use buildType
+        // instead, but then all the samples that need to disable rv64 would
+        // have to do it twice (once for release and once for debug). Since the
+        // sanitizers sample is the only one that needs this behavior, I'd
+        // rather keep the mess here rather than spread it around.
+        ndk {
+            abiFilters.clear()
+        }
     }
 
     buildTypes {
+        // Now that the defaultConfig abiFilters have been cleared, the
+        // buildType abiFilters will actually have an effect. Enable all ABIs,
+        // since that's what we want for most of the sanitizers.
+        debug {
+            ndk {
+                abiFilters(
+                    "arm64-v8a",
+                    "armeabi-v7a",
+                    "riscv64",
+                    "x86",
+                    "x86_64",
+                )
+            }
+        }
+
+        release {
+            ndk {
+                abiFilters(
+                    "arm64-v8a",
+                    "armeabi-v7a",
+                    "riscv64",
+                    "x86",
+                    "x86_64",
+                )
+            }
+        }
+
         // HWASan for devices starting from Android 14. Does no longer require a special system image.
         // See https://developer.android.com/ndk/guides/hwasan.
         hwasan {
@@ -36,6 +86,11 @@ android {
                 }
             }
             ndk {
+                // The defaultConfig's abiFilters were cleared above, but then
+                // we also populated the debug buildType's abiFilters with all
+                // ABIs, which the hwasan buildType inherits. We only want
+                // arm64-v8a here.
+                abiFilters.clear()
                 abiFilters "arm64-v8a"
             }
         }

unit-test/app/build.gradle

@@ -12,6 +12,12 @@ android {
         versionName "1.0"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+
+        ndk {
+            // junit-gtest and googletest don't currently (August 2025) include
+            // riscv64 libraries.
+            abiFilters.remove("riscv64")
+        }
     }
 
     externalNativeBuild {