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layout: doc title: “Starboard: gyp_configuration Reference Guide”

Variables
abort_on_allocation_failure Halt execution on failure to allocate memory. The default value is 1.
cobalt Whether Cobalt is being built. The default value is 1.
cobalt_config Contains the current build configuration. The default value is 'gold'.
cobalt_egl_swap_interval Cobalt will call eglSwapInterval() and specify this value before calling eglSwapBuffers() each frame. The default value is 1.
cobalt_enable_jit Disable JIT and run in interpreter-only mode by default. It can be set to 1 to run in JIT mode. For SpiderMonkey in particular, we have found that disabling JIT often results in faster JavaScript execution and lower memory usage. Setting this to 1 on a platform or engine for which there is no JIT implementation is a no-op. Setting this to 0 on an engine for which there is a JIT implementation is a platform configuration error. The default value is 0.
cobalt_enable_lib Enables embedding Cobalt as a shared library within another app. This requires a ‘lib’ starboard implementation for the corresponding platform. The default value is '<(sb_enable_lib)'.
cobalt_fastbuild Contains the current build configuration. The default value is 0.
cobalt_font_package Contains the current font package selection. This can be used to trade font quality, coverage, and latency for different font package sizes. The font package can be one of the following options:standard - The default package. It includes all sans-serif, serif, and FCC fonts, non-CJK fallback fonts in both ‘normal’ and ‘bold’ weights, ‘normal’ weight CJK (‘bold’ weight CJK is synthesized from it), and historic script fonts. This package is ~31.4MB.limited_with_jp - A significantly smaller package than ‘standard’. This package removes all but ‘normal’ and ‘bold’ weighted sans-serif and serif, removes the FCC fonts (which must be provided by the system or downloaded from the web), removes the ‘bold’ weighted non-CJK fallback fonts (the ‘normal’ weight is still included and is used to synthesize bold), and replaces standard CJK with low quality CJK. However, higher quality Japanese is still included. Because low quality CJK cannot synthesize bold, bold glyphs are unavailable in Chinese and Korean. Historic script fonts are not included. This package is ~11.5MB.limited - A smaller package than ‘limited_with_jp’. The two packages are identical with the exception that ‘limited’ does not include the higher quality Japanese font; instead it relies on low quality CJK for all CJK characters. Because low quality CJK cannot synthesize bold, bold glyphs are unavailable in Chinese, Japanese, and Korean. This package is ~8.3MB.minimal - The smallest possible font package. It only includes Roboto's Basic Latin characters. Everything else must be provided by the system or downloaded from the web. This package is ~40.0KB. NOTE: When bold is needed, but unavailable, it is typically synthesized, resulting in lower quality glyphs than those generated directly from a bold font. However, this does not occur with low quality CJK, which is not high enough quality to synthesize. Its glyphs always have a ‘normal’ weight. The default value is 'standard'.
cobalt_font_package_override_fallback_emoji Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_fallback_historic Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_fallback_lang_cjk Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_fallback_lang_cjk_low_quality Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_fallback_lang_jp Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_fallback_lang_non_cjk Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_fallback_symbols Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_named_fcc_fonts Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_named_sans_serif Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_font_package_override_named_serif Font package overrides can be used to modify the files included within the selected package. The following values are available: -1 -- The package value for the specified category is not overridden. 0 -- The package value is overridden and no fonts for the specified category are included. 1 -- The package value is overridden and fonts from the specified category with a weight of ‘normal’ and a style of ‘normal’ are included. 2 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or bold' and a style of ‘normal’ are included. 3 -- The package value is overridden and fonts from the specified category with a weight of either ‘normal’ or ‘bold’ and a style of either ‘normal’ or ‘italic’ are included. 4 -- The package value is overridden and all available fonts from the specified category are included. This may include additional weights beyond ‘normal’ and ‘bold’. See content/fonts/README.md for details on the specific values used by each of the packages use for the various font categories. The default value is -1.
cobalt_gc_zeal Can be set to enable zealous garbage collection, if
cobalt_media_buffer_alignment The media buffer will be allocated using the following alignment. Set this to a larger value may increase the memory consumption of media buffers. The default value is 0.
cobalt_media_buffer_allocation_unit When the media stack needs more memory to store media buffers, it will allocate extra memory in units of
cobalt_media_buffer_initial_capacity The amount of memory that will be used to store media buffers allocated during system startup. To allocate a large chunk at startup helps with reducing fragmentation and can avoid failures to allocate incrementally. This can be set to 0. The default value is 21 * 1024 * 1024.
cobalt_media_buffer_non_video_budget Specifies the maximum amount of memory used by audio or text buffers of media source before triggering a garbage collection. A large value will cause more memory being used by audio buffers but will also make JavaScript app less likely to re-download audio data. Note that the JavaScript app may experience significant difficulty if this value is too low. The default value is 5 * 1024 * 1024.
cobalt_media_buffer_padding Extra bytes allocated at the end of a media buffer to ensure that the buffer can be use optimally by specific instructions like SIMD. Set to 0 to remove any padding. The default value is 0.
cobalt_media_buffer_pool_allocate_on_demand When either
cobalt_media_buffer_progressive_budget The memory used when playing mp4 videos that is not in DASH format. The resolution of such videos shouldn't go beyond 1080p. Its value should be less than the sum of ‘cobalt_media_buffer_non_video_budget’ and ‘cobalt_media_buffer_video_budget_1080p’ but not less than 8 MB. The default value is 12 * 1024 * 1024.
cobalt_media_buffer_storage_type This can be set to “memory” or “file”. When it is set to “memory”, the media buffers will be stored in main memory allocated by SbMemory functions. When it is set to “file”, the media buffers will be stored in a temporary file in the system cache folder acquired by calling SbSystemGetPath() with “kSbSystemPathCacheDirectory”. Note that when its value is “file” the media stack will still allocate memory to cache the the buffers in use. The default value is 'memory'.
cobalt_media_buffer_video_budget_1080p Specifies the maximum amount of memory used by video buffers of media source before triggering a garbage collection when the video resolution is lower than 1080p (1920x1080). A large value will cause more memory being used by video buffers but will also make JavaScript app less likely to re-download video data. Note that the JavaScript app may experience significant difficulty if this value is too low. The default value is 16 * 1024 * 1024.
cobalt_media_buffer_video_budget_4k Specifies the maximum amount of memory used by video buffers of media source before triggering a garbage collection when the video resolution is lower than 4k (3840x2160). A large value will cause more memory being used by video buffers but will also make JavaScript app less likely to re-download video data. Note that the JavaScript app may experience significant difficulty if this value is too low. The default value is 60 * 1024 * 1024.
cobalt_media_source_2016 Use media source extension implementation that is conformed to the Candidate Recommandation of July 5th 2016. The default value is '<(cobalt_media_source_2016)'.
cobalt_minimum_frame_time_in_milliseconds Allow throttling of the frame rate. This is expressed in terms of milliseconds and can be a floating point number. Keep in mind that swapping frames may take some additional processing time, so it may be better to specify a lower delay. For example, ‘33’ instead of ‘33.33’ for 30 Hz refresh. The default value is '16.0'.
cobalt_platform_dependencies List of platform-specific targets that get compiled into cobalt. The default value is [].
cobalt_user_on_exit_strategy This variable defines what Cobalt's preferred strategy should be for handling internally triggered application exit requests (e.g. the user chooses to back out of the application).stop - The application should call SbSystemRequestStop() on exit, resulting in a complete shutdown of the application.suspend - The application should call SbSystemRequestSuspend() on exit, resulting in the application being “minimized”.noexit - The application should never allow the user to trigger an exit, this will be managed by the system. The default value is 'stop'.
cobalt_version Build version number. The default value is 0.
cobalt_webapi_extension_generated_header_idl_files We need to define some variables inside of an inner ‘variables’ scope so that they can be referenced by other outer variables here. Also, it allows for the specification of default values that get referenced by a top level scope. The default value is [].
cobalt_webapi_extension_source_idl_files We need to define some variables inside of an inner ‘variables’ scope so that they can be referenced by other outer variables here. Also, it allows for the specification of default values that get referenced by a top level scope. The default value is [].
compiler_flags_<config> The following configurations are supported: [default]c_debugc_develc_goldc_hostc_qacc_debugcc_develcc_goldcc_hostcc_qadebugdevelgoldhostqa
custom_media_session_client Set to 1 to enable a custom MediaSessionClient. The default value is 0.
default_javascript_engine The only currently-supported Javascript engine is ‘mozjs-45’. The default value is 'mozjs-45'.
default_renderer_options_dependency Override this value to adjust the default rasterizer setting for your platform. The default value is '<(DEPTH)/cobalt/renderer/default_options_starboard.gyp:default_options'.
defines_debug The default value is [].
defines_devel The default value is [].
defines_gold The default value is [].
defines_host The default value is [].
defines_qa The default value is [].
enable_account_manager Set to 1 to enable H5vccAccountManager. The default value is 0.
enable_crash_log Set to 1 to enable H5vccCrashLog. The default value is 0.
enable_map_to_mesh Enable support for the map to mesh filter, which is primarily used to implement spherical video playback. The default value is 0.
enable_spdy Set to 1 to compile with SPDY support. The default value is 0.
enable_sso Set to 1 to enable H5vccSSO (Single Sign On). The default value is 0.
enable_xhr_header_filtering Set to 1 to enable filtering of HTTP headers before sending. The default value is 0.
fallback_splash_screen_url The URL of default build time splash screen - see cobalt/doc/splash_screen.md for information about this. The default value is 'none'.
final_executable_type The variables allow changing the target type on platforms where the native code may require an additional packaging step (ex. Android). The default value is 'executable'.
gl_type The source of EGL and GLES headers and libraries. Valid values (case and everything sensitive!):none - No EGL + GLES implementation is available on this platform.system_gles3 - Use the system implementation of EGL + GLES3. The headers and libraries must be on the system include and link paths.system_gles2 - Use the system implementation of EGL + GLES2. The headers and libraries must be on the system include and link paths.glimp - Cobalt's own EGL + GLES2 implementation. This requires a valid Glimp implementation for the platform.angle - A DirectX-to-OpenGL adaptation layer. This requires a valid ANGLE implementation for the platform. Choosing an unsupported value will result in a GYP error: “cobalt/renderer/egl_and_gles/egl_and_gles_<gl_type>.gyp not found” The default value is 'system_gles2'.
gtest_target_type The variables allow changing the target type on platforms where the native code may require an additional packaging step (ex. Android). The default value is 'executable'.
host_os Contains the name of the hosting OS. The value is defined by the gyp wrapper script. The default value is 'win'.
image_cache_capacity_multiplier_when_playing_video Modifying this value to be non-1.0f will result in the image cache capacity being cleared and then temporarily reduced for the duration that a video is playing. This can be useful for some platforms if they are particularly constrained for (GPU) memory during video playback. When playing a video, the image cache is reduced to: image_cache_size_in_bytes * image_cache_capacity_multiplier_when_playing_video. The default value is '1.0f'.
image_cache_size_in_bytes Determines the capacity of the image cache, which manages image surfaces downloaded from a web page. While it depends on the platform, often (and ideally) these images are cached within GPU memory. Set to -1 to automatically calculate the value at runtime, based on features like windows dimensions and the value of SbSystemGetTotalGPUMemory(). The default value is -1.
in_app_dial Set to 1 to build with DIAL support. The default value is 0.
javascript_engine The only currently-supported Javascript engine is ‘mozjs-45’. The default value is '<(default_javascript_engine)'.
linker_flags_<config> The following configurations are supported: [default]debugdevelgoldhostqa
local_font_cache_size_in_bytes Determines the capacity of the local font cache, which manages all fonts loaded from local files. Newly encountered sections of font files are lazily loaded into the cache, enabling subsequent requests to the same file sections to be handled via direct memory access. Once the limit is reached, further requests are handled via file stream. Setting the value to 0 disables memory caching and causes all font file accesses to be done using file streams. The default value is 16 * 1024 * 1024.
max_cobalt_cpu_usage Max Cobalt CPU usage specifies that the cobalt program should keep it's size below the specified size. A value of -1 causes this value to be assumed from the starboard API function: SbSystemGetTotalCPUMemory(). The default value is -1.
max_cobalt_gpu_usage Max Cobalt GPU usage specifies that the cobalt program should keep it's size below the specified size. A value of -1 causes this value to be assumed from the starboard API function: SbSystemGetTotalGPUMemory(). The default value is -1.
mesh_cache_size_in_bytes Determines the capacity of the mesh cache. Each mesh is held compressed in main memory, to be inflated into a GPU buffer when needed for projection. When set to ‘auto’, will be adjusted according to whether the enable_map_to_mesh is true or not. If enable_map_to_mesh is false, then the mesh cache size will be set to 0. The default value is 'auto'.
mozjs_garbage_collection_threshold_in_bytes Determines the size of garbage collection threshold. After this many bytes have been allocated, the SpiderMonkey garbage collector will run. Lowering this has been found to reduce performance and decrease JavaScript memory usage. For example, we have measured on at least one platform that performance becomes 7% worse on average in certain cases when adjusting this number from 8MB to 1MB. The default value is 8 * 1024 * 1024.
offscreen_target_cache_size_in_bytes Determines the amount of GPU memory the offscreen target atlases will use. This is specific to the direct-GLES rasterizer and serves a similar purpose as the surface_cache_size_in_bytes, but caches any render tree nodes which require skia for rendering. Two atlases will be allocated from this memory or multiple atlases of the frame size if the limit allows. It is recommended that enough memory be reserved for two RGBA atlases about a quarter of the frame size. The default value is -1.
platform_libraries The default value is [].
rasterizer_type Defines what kind of rasterizer will be used. This can be adjusted to force a stub graphics implementation or software graphics implementation. It can be one of the following options:direct-gles - Uses a light wrapper over OpenGL ES to handle most draw elements. This will fall back to the skia hardware rasterizer for some render tree node types, but is generally faster on the CPU and GPU. This can handle 360 rendering.hardware - As much hardware acceleration of graphics commands as possible. This uses skia to wrap OpenGL ES commands. Required for 360 rendering.software - Perform most rasterization using the CPU and only interact with the GPU to send the final image to the output window.stub - Stub graphics rasterization. A rasterizer object will still be available and valid, but it will do nothing. The default value is 'direct-gles'.
reduce_cpu_memory_by When specified this value will reduce the cpu memory consumption by the specified amount. -1 disables the value. When this value is specified then max_cobalt_cpu_usage will not be used in memory_constrainer, but will still be used for triggering a warning if the engine consumes more memory than this value specifies. The default value is -1.
reduce_gpu_memory_by When specified this value will reduce the gpu memory consumption by the specified amount. -1 disables the value. When this value is specified then max_cobalt_gpu_usage will not be used in memory_constrainer, but will still be used for triggering a warning if the engine consumes more memory than this value specifies. The default value is -1.
remote_font_cache_size_in_bytes Determines the capacity of the remote font cache, which manages all fonts downloaded from a web page. The default value is 4 * 1024 * 1024.
render_dirty_region_only If set to 1, will enable support for rendering only the regions of the display that are modified due to animations, instead of re-rendering the entire scene each frame. This feature can reduce startup time where usually there is a small loading spinner animating on the screen. On GLES renderers, Cobalt will attempt to implement this support by using eglSurfaceAttrib(..., EGL_SWAP_BEHAVIOR, EGL_BUFFER_PRESERVED), otherwise the dirty region will be silently disabled. On Blitter API platforms, if this is enabled, we explicitly create an extra offscreen full-size intermediate surface to render into. Note that some GLES driver implementations may internally allocate an extra full screen surface to support this feature, and many have been noticed to not properly support this functionality (but they report that they do), and for these reasons this value is defaulted to 0. The default value is 0.
sb_disable_microphone_idl When this is set to true, the web bindings for the microphone are disabled The default value is 0.
sb_enable_lib Enables embedding Cobalt as a shared library within another app. This requires a ‘lib’ starboard implementation for the corresponding platform. The default value is '<(sb_enable_lib)'.
sb_libevent_method The event polling mechanism available on this platform to support libevent. Platforms may redefine to ‘poll’ if necessary. Other mechanisms, e.g. devpoll, kqueue, select, are not yet supported. The default value is 'epoll'.
sb_media_platform Used to pick a proper media platform. The default value is 'starboard'.
sb_pedantic_warnings Enabling this variable enables pedantic levels of warnings for the current toolchain. The default value is 0.
sb_static_contents_output_base_dir Directory path to static contents. The default value is '<(PRODUCT_DIR)/content'.
sb_static_contents_output_data_dir Directory path to static contents' data. The default value is '<(PRODUCT_DIR)/content/data'.
sb_target_platform The target platform id as a string, like ‘linux-x64x11’, ‘win32’, etc.. The default value is ''.
scratch_surface_cache_size_in_bytes Determines the capacity of the scratch surface cache. The scratch surface cache facilitates the reuse of temporary offscreen surfaces within a single frame. This setting is only relevant when using the hardware-accelerated Skia rasterizer. The default value is 0.
skia_cache_size_in_bytes Determines the capacity of the skia cache. The Skia cache is maintained within Skia and is used to cache the results of complicated effects such as shadows, so that Skia draw calls that are used repeatedly across frames can be cached into surfaces. This setting is only relevant when using the hardware-accelerated Skia rasterizer (e.g. as opposed to the Blitter API). The default value is 4 * 1024 * 1024.
skia_glyph_atlas_height Determines the size in pixels of the glyph atlas where rendered glyphs are cached. The resulting memory usage is 2 bytes of GPU memory per pixel. When a value is used that is too small, thrashing may occur that will result in visible stutter. Such thrashing is more likely to occur when CJK language glyphs are rendered and when the size of the glyphs in pixels is larger, such as for higher resolution displays. The negative default values indicates to the engine that these settings should be automatically set. The default value is '-1'.
skia_glyph_atlas_width Determines the size in pixels of the glyph atlas where rendered glyphs are cached. The resulting memory usage is 2 bytes of GPU memory per pixel. When a value is used that is too small, thrashing may occur that will result in visible stutter. Such thrashing is more likely to occur when CJK language glyphs are rendered and when the size of the glyphs in pixels is larger, such as for higher resolution displays. The negative default values indicates to the engine that these settings should be automatically set. The default value is '-1'.
software_surface_cache_size_in_bytes Only relevant if you are using the Blitter API. Determines the capacity of the software surface cache, which is used to cache all surfaces that are rendered via a software rasterizer to avoid re-rendering them. The default value is 8 * 1024 * 1024.
starboard_path The relative path from src/ to the directory containing the starboard_platform.gyp file. It is currently set to ‘starboard/<(target_arch)’ to make semi-starboard platforms work. moved to starboard. The default value is 'starboard/<(target_arch)'.
surface_cache_size_in_bytes Determines the capacity of the surface cache. The surface cache tracks which render tree nodes are being re-used across frames and stores the nodes that are most CPU-expensive to render into surfaces. The default value is 0.
target_os The operating system of the target, separate from the target_arch. In many cases, an ‘unknown’ value is fine, but, if set to ‘linux’, then we can assume some things, and it'll save us some configuration time. The default value is 'unknown'.
tizen_os Temporary indicator for Tizen - should eventually move to feature defines. The default value is 0.