diff --git a/target/board/mainline_arm64/BoardConfig.mk b/target/board/mainline_arm64/BoardConfig.mk
index ea2b3c5..7cb2609 100644
--- a/target/board/mainline_arm64/BoardConfig.mk
+++ b/target/board/mainline_arm64/BoardConfig.mk
@@ -32,8 +32,9 @@
 AB_OTA_UPDATER := true
 AB_OTA_PARTITIONS := system
 
-BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE := ext4
 BOARD_PRODUCTIMAGE_FILE_SYSTEM_TYPE := ext4
+BOARD_SYSTEM_EXTIMAGE_FILE_SYSTEM_TYPE := ext4
+BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE := ext4
 
 # Mainline devices support apex
 # TODO: move this to BoardConfigMainlineCommon. Currently, GSI wants flattened
diff --git a/target/board/mainline_x86/BoardConfig.mk b/target/board/mainline_x86/BoardConfig.mk
new file mode 100644
index 0000000..a20d17c
--- /dev/null
+++ b/target/board/mainline_x86/BoardConfig.mk
@@ -0,0 +1,35 @@
+#
+# Copyright (C) 2019 The Android Open Source Project
+#
+# 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.
+#
+
+TARGET_ARCH := x86
+TARGET_ARCH_VARIANT := x86
+TARGET_CPU_ABI := x86
+
+include build/make/target/board/BoardConfigMainlineCommon.mk
+
+TARGET_NO_KERNEL := true
+
+# Build generic A/B format system-only OTA.
+AB_OTA_UPDATER := true
+AB_OTA_PARTITIONS := system
+
+BOARD_PRODUCTIMAGE_FILE_SYSTEM_TYPE := ext4
+BOARD_SYSTEM_EXTIMAGE_FILE_SYSTEM_TYPE := ext4
+BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE := ext4
+
+# Mainline devices support apex
+# TODO: move this to product makefile and use updatable_apex.mk
+TARGET_FLATTEN_APEX := false
diff --git a/target/board/mainline_x86_arm/BoardConfig.mk b/target/board/mainline_x86_arm/BoardConfig.mk
new file mode 100644
index 0000000..6b282c2
--- /dev/null
+++ b/target/board/mainline_x86_arm/BoardConfig.mk
@@ -0,0 +1,40 @@
+#
+# Copyright (C) 2019 The Android Open Source Project
+#
+# 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.
+#
+
+TARGET_ARCH := x86
+TARGET_ARCH_VARIANT := x86
+TARGET_CPU_ABI := x86
+
+TARGET_NATIVE_BRIDGE_ARCH := arm
+TARGET_NATIVE_BRIDGE_ARCH_VARIANT := armv7-a-neon
+TARGET_NATIVE_BRIDGE_CPU_VARIANT := generic
+TARGET_NATIVE_BRIDGE_ABI := armeabi-v7a armeabi
+
+include build/make/target/board/BoardConfigMainlineCommon.mk
+
+TARGET_NO_KERNEL := true
+
+# Build generic A/B format system-only OTA.
+AB_OTA_UPDATER := true
+AB_OTA_PARTITIONS := system
+
+BOARD_PRODUCTIMAGE_FILE_SYSTEM_TYPE := ext4
+BOARD_SYSTEM_EXTIMAGE_FILE_SYSTEM_TYPE := ext4
+BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE := ext4
+
+# Mainline devices support apex
+# TODO: move this to product makefile and use updatable_apex.mk
+TARGET_FLATTEN_APEX := false
diff --git a/target/product/AndroidProducts.mk b/target/product/AndroidProducts.mk
index 174916d..ca4ed2c 100644
--- a/target/product/AndroidProducts.mk
+++ b/target/product/AndroidProducts.mk
@@ -55,6 +55,8 @@
     $(LOCAL_DIR)/gsi_arm64.mk \
     $(LOCAL_DIR)/mainline_arm64.mk \
     $(LOCAL_DIR)/mainline_system_arm64.mk \
+    $(LOCAL_DIR)/mainline_system_x86.mk \
+    $(LOCAL_DIR)/mainline_system_x86_arm.mk \
     $(LOCAL_DIR)/sdk_arm64.mk \
     $(LOCAL_DIR)/sdk.mk \
     $(LOCAL_DIR)/sdk_phone_arm64.mk \
diff --git a/target/product/mainline_system_x86.mk b/target/product/mainline_system_x86.mk
new file mode 100644
index 0000000..ac33068
--- /dev/null
+++ b/target/product/mainline_system_x86.mk
@@ -0,0 +1,40 @@
+#
+# Copyright (C) 2019 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+#
+# All components inherited here go to system image
+#
+$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call enforce-product-packages-exist,)
+
+# Enable mainline checking
+PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
+
+PRODUCT_BUILD_CACHE_IMAGE := false
+PRODUCT_BUILD_ODM_IMAGE := false
+PRODUCT_BUILD_PRODUCT_IMAGE  := false
+PRODUCT_BUILD_RAMDISK_IMAGE := false
+PRODUCT_BUILD_SYSTEM_IMAGE := true
+PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
+PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
+PRODUCT_BUILD_USERDATA_IMAGE := false
+PRODUCT_BUILD_VENDOR_IMAGE := false
+
+PRODUCT_NAME := mainline_system_x86
+PRODUCT_DEVICE := mainline_x86
+PRODUCT_BRAND := generic
+PRODUCT_SHIPPING_API_LEVEL := 28
+PRODUCT_RESTRICT_VENDOR_FILES := all
diff --git a/target/product/mainline_system_x86_arm.mk b/target/product/mainline_system_x86_arm.mk
new file mode 100644
index 0000000..0ed86cc
--- /dev/null
+++ b/target/product/mainline_system_x86_arm.mk
@@ -0,0 +1,40 @@
+#
+# Copyright (C) 2019 The Android Open Source Project
+#
+# 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.
+#
+
+#
+# All components inherited here go to system image
+#
+$(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
+$(call enforce-product-packages-exist,)
+
+# Enable mainline checking
+PRODUCT_ENFORCE_ARTIFACT_PATH_REQUIREMENTS := true
+
+PRODUCT_BUILD_CACHE_IMAGE := false
+PRODUCT_BUILD_ODM_IMAGE := false
+PRODUCT_BUILD_PRODUCT_IMAGE  := false
+PRODUCT_BUILD_RAMDISK_IMAGE := false
+PRODUCT_BUILD_SYSTEM_IMAGE := true
+PRODUCT_BUILD_SYSTEM_EXT_IMAGE := false
+PRODUCT_BUILD_SYSTEM_OTHER_IMAGE := false
+PRODUCT_BUILD_USERDATA_IMAGE := false
+PRODUCT_BUILD_VENDOR_IMAGE := false
+
+PRODUCT_NAME := mainline_system_x86_arm
+PRODUCT_DEVICE := mainline_x86_arm
+PRODUCT_BRAND := generic
+PRODUCT_SHIPPING_API_LEVEL := 28
+PRODUCT_RESTRICT_VENDOR_FILES := all