Enable riscv64 for most samples.

This isn't a supported ABI yet, but I want to enable it here to get
ahead of some of that work. I just disabled that config for any of the
samples which don't already work with rv64. There are a few reasons why
some samples don't work with rv64 yet, noted in the comments next to the
line that disables the ABI. Most of them are because some upstream
dependency doesn't yet include rv64 libraries, and there's nothing we
can do about that here.

Author: Dan Albert

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 +32,14 @@ class AndroidApplicationConventionPlugin : Plugin<Project> {
                             arguments.add("-DANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES=ON")
                         }
                     }
+
+                    ndk {
+                        // This 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.add("riscv64")
+                    }
                 }
                 compileOptions {
                     sourceCompatibility = Versions.JAVA

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

@@ -35,6 +35,13 @@ class AndroidLibraryConventionPlugin : Plugin<Project> {
                             arguments.add("-DANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES=ON")
                         }
                     }
+                    ndk {
+                        // This 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.add("riscv64")
+                    }
                 }
                 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 +4,20 @@ 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
+            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 {