Asuro/doc/lvglh/lv_conf.md

lv_conf.h

LVGL v9.2.2 configuration header tailored for the Asuro bare-metal kernel environment.

Overview

This file configures the LVGL graphics library for use inside the Asuro kernel, where no standard C library, operating system, or GPU hardware is available. It selects a 32-bit XRGB8888 color depth to match the VESA framebuffer, routes all stdlib functionality through LVGL's built-in implementations, enables only the software renderer, and disables every hardware backend, filesystem driver, and image decoder. The result is a minimal but functional GUI stack that runs entirely in kernel space.

Configuration Options / Defines

Color Settings

LV_COLOR_DEPTH

Value: 32. Matches the VESA XRGB8888 framebuffer used by Asuro.

Standard Library Wrappers

LV_USE_STDLIB_MALLOC / LV_USE_STDLIB_STRING / LV_USE_STDLIB_SPRINTF

Value: LV_STDLIB_BUILTIN. All three are set to use LVGL's own built-in implementations since no libc is available in the bare-metal environment.

Memory Pool

LV_MEM_SIZE

Value: 256 * 1024U (256 KB). Size of LVGL's internal memory pool for widget allocations and draw buffers.

LV_MEM_POOL_EXPAND_SIZE

Value: 0. Pool expansion is disabled; the 256 KB allocation is fixed.

LV_MEM_ADR

Value: 0. LVGL allocates the pool itself rather than using a fixed address.

HAL Settings

LV_DEF_REFR_PERIOD

Value: 33 (milliseconds). Targets approximately 30 frames per second.

LV_DPI_DEF

Value: 96. Standard screen DPI assumption.

Operating System

LV_USE_OS

Value: LV_OS_NONE. No OS abstraction layer; LVGL runs in a bare-metal cooperative model.

Rendering Configuration

LV_USE_DRAW_SW

Value: 1. The software renderer is the sole rendering backend.

Only the color formats actually used are enabled within the software renderer:

Define	Value	Description
LV_DRAW_SW_SUPPORT_XRGB8888	1	Primary framebuffer format
LV_DRAW_SW_SUPPORT_ARGB8888	1	Alpha-blended surfaces
LV_DRAW_SW_SUPPORT_RGB888	1	24-bit fallback
LV_DRAW_SW_SUPPORT_RGB565	0	Disabled
All other formats	0	Disabled

LV_DRAW_SW_COMPLEX

Value: 1. Enables complex draw operations (shadows, rounded corners). Shadow cache is disabled (LV_DRAW_SW_SHADOW_CACHE_SIZE = 0); circle cache is set to 4 entries.

LV_DRAW_LAYER_SIMPLE_BUF_SIZE

Value: 24 * 1024 (24 KB). Buffer for simple layer rendering.

GPU Backends

All GPU-accelerated backends are disabled: VGLite, PXP, Dave2D, SDL, VG-Lite.

Logging

LV_USE_LOG

Value: 1. Logging is enabled at LV_LOG_LEVEL_WARN. Printf-based logging, timestamps, and file/line info are all disabled to reduce overhead. All trace categories (memory, timer, indev, display refresh, events, object creation, layout, animation, cache) are disabled.

Assertions

LV_USE_ASSERT_NULL / LV_USE_ASSERT_MALLOC

Value: 1. Null-pointer and malloc-failure assertions are active.

LV_ASSERT_HANDLER

Value: {} (no-op). The assert handler intentionally does nothing to avoid hanging the kernel on a failed assertion.

Fonts

LV_FONT_MONTSERRAT_14

Value: 1. The only built-in Montserrat size enabled.

LV_FONT_DEFAULT

Value: &lv_font_montserrat_14. All other Montserrat sizes (8--48), compressed variants, and alternative font families (DejaVu, SimSun, UNSCII) are disabled.

Text Settings

LV_TXT_ENC

Value: LV_TXT_ENC_UTF8. UTF-8 text encoding. BiDi and Arabic/Persian character support are disabled.

Widgets

Enabled widgets: AnimImg, Arc, Bar, Button, ButtonMatrix, Checkbox, Dropdown, Image, Keyboard, Label, Line, List, MsgBox, Roller, Slider, Spinner, Switch, TextArea, Table, TabView, Win.

Disabled widgets: Calendar, Canvas, Chart, ImageButton, LED, Lottie, Menu, Scale, Span, SpinBox, TileView.

Themes

LV_USE_THEME_DEFAULT

Value: 1. Dark mode enabled (LV_THEME_DEFAULT_DARK = 1) with 80 ms transition time.

LV_USE_THEME_SIMPLE

Value: 1.

LV_USE_THEME_MONO

Value: 0.

Layouts

Both Flex and Grid layout engines are enabled.

Third-Party Libraries

All filesystem drivers are disabled (stdio, POSIX, Win32, FatFS, MemFS, LittleFS). All image decoders are disabled (PNG, BMP, JPEG, GIF, RLE). FreeType, TinyTTF, Rlottie, vector graphics, LZ4, and FFmpeg are all disabled.

Device Drivers

All platform-specific device drivers are disabled (SDL, X11, Wayland, Linux FBDEV, Linux DRM, NuttX, various SPI display controllers, Windows, OpenGLES, QNX). Display and input are handled by Asuro's own HAL layer.

Examples and Demos

All built-in examples and demo applications are disabled.

Notes

• The configuration is designed for minimal footprint. Features are enabled only when required by the Asuro desktop shell.
• Since no libc is linked, all string, memory, and formatting operations fall through to LVGL's internal implementations.
• The assert handler is a deliberate no-op to prevent the kernel from halting on non-critical UI assertion failures.
• The 256 KB memory pool is fixed and cannot expand at runtime. UI complexity must stay within this budget.