 The Frame Buffer Device API in the Linux Kernel documentation

Primary kernel-interface documentation, §2 Types and visuals (packed pixels, padding and formats); §3 Screen information, fb_fix_screeninfo.line_length in bytes; §4 Format configuration. Related primary introduction docs.kernel.org/fb/framebuffer.html §§0–1 describes graphics-memory access. Documentation distinguishes recommended behavior from driver variation; no API-specific promise applied to all graphics interfaces.