Usplash was a splash screen system used by various Linux distributions, most notably Ubuntu, during the boot process. Its primary function was to provide a graphical boot screen, displaying a logo, progress bar, or animated elements (like the famous loading dots) while the operating system initialized. This helped to obscure the textual console messages that scrolled by during startup, providing a more aesthetically pleasing and user-friendly experience.
Usplash operated by writing directly to the kernel framebuffer, allowing it to display graphics even before the full graphical environment (like X Window System) was loaded. It would typically take over from the kernel's text console and display its graphical animation until the desktop environment's display manager (e.g., GDM, LightDM) took control.
Introduced in Ubuntu's early versions, Usplash served as the default boot splash system for several releases. It was designed to provide visual feedback to the user during the potentially long boot times, reassuring them that the system was active and progressing.
Over time, limitations of Usplash, particularly its reliance on the framebuffer and challenges with newer display technologies like Kernel Mode Setting (KMS), led to its deprecation. It was eventually replaced by Plymouth in Ubuntu 9.10 (Karmic Koala) and subsequent releases. Plymouth offered more advanced features, better integration with KMS, and a more robust framework for boot splash screens.