ConfigStore

In Android, system properties are stored in the ConfigStore class. ConfigStore uses build flags to store config values in the vendor partition, and a service in the system partition accesses those values using HIDL.

System properties use PRODUCT_DEFAULT_PROPERTY_OVERRIDES to store system properties in default.prop in the vendor partition, and the service uses sysprop to read those properties.

The ConfigStore HAL remains in AOSP to support legacy vendor partitions. On devices running Android 10, surfaceflinger reads system properties first; if no system property is defined for a config item in SurfaceFlingerProperties.sysprop, surfaceflinger falls back to the ConfigStore HAL.

Build flags and system properties

Each build flag in ConfigStore has a matching system property, as shown in the following table.

Build flags System properties
TARGET_FORCE_HWC_FOR_VIRTUAL_DISPLAYS ro.surface_flinger.force_hwc_copy_for_virtual_displays
TARGET_HAS_HDR_DISPLAY ro.surface_flinger.has_HDR_display
TARGET_HAS_WIDE_COLOR_DISPLAY ro.surface_flinger.has_wide_color_display
NUM_FRAMEBUFFER_SURFACE_BUFFERS ro.surface_flinger.max_frame_buffer_acquired_buffers
MAX_VIRTUAL_DISPLAY_DIMENSION ro.surface_flinger.max_virtual_display_dimension
PRIMARY_DISPLAY_ORIENTATION ro.surface_flinger.primary_display_orientation
PRESENT_TIME_OFFSET_FROM_VSYNC_NS ro.surface_flinger.present_time_offset_from_vsync_ns
TARGET_RUNNING_WITHOUT_SYNC_FRAMEWORK ro.surface_flinger.running_without_sync_framework
SF_START_GRAPHICS_ALLOCATOR_SERVICE ro.surface_flinger.start_graphics_allocator_service
TARGET_USE_CONTEXT_PRIORITY ro.surface_flinger.use_context_priority
USE_VR_FLINGER ro.surface_flinger.use_vr_flinger
VSYNC_EVENT_PHASE_OFFSET_NS ro.surface_flinger.vsync_event_phase_offset_ns
SF_VSYNC_EVENT_PHASE_OFFSET_NS ro.surface_flinger.vsync_sf_event_phase_offset_ns

New system properties

Android 10 includes the following new system properties:

  • ro.surface_flinger.default_composition_dataspace
  • ro.surface_flinger.default_composition_pixel_format
  • ro.surface_flinger.use_color_management
  • ro.surface_flinger.wcg_composition_dataspace
  • ro.surface_flinger.wcg_composition_pixel_format
  • ro.surface_flinger.display_primary_red
  • ro.surface_flinger.display_primary_green
  • ro.surface_flinger.display_primary_blue
  • ro.surface_flinger.display_primary_white
  • ro.surface_flinger.protected_contents
  • ro.surface_flinger.set_idle_timer_ms
  • ro.surface_flinger.set_touch_timer_ms
  • ro.surface_flinger.use_smart_90_for_video
  • ro.surface_flinger.protected_contents
  • ro.surface_flinger.support_kernel_idle_timer

For details on these properties, refer to frameworks/native/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop.

Use SurfaceFlingerProperties

In the following examples for the SurfaceFlingerProperties library, the function name is api_name in SurfaceFlingerProperties.sysprop. 

cc_binary {
    name: "cc_client",
    srcs: ["baz.cpp"],
    shared_libs: ["SurfaceFlingerProperties"],
}
java_library {
    name: "JavaClient",
    srcs: ["foo/bar.java"],
    libs: ["SurfaceFlingerProperties"],
}
 
import android.sysprop.SurfaceFlingerProperties;
...

static void foo() {
    ...
    boolean temp = SurfaceFlingerProperties.vsync_event_phase_offset_ns().orElse(true);
    ...
}
...
 
#include <SurfaceFlingerProperties.sysprop.h>
using namespace android::sysprop;

...

void bar() {
    ...
    bool temp = SurfaceFlingerProperties::vsync_event_phase_offset_ns(true);
    ...
}
...