Abstract: A modular microcode (uCode) patch method to support runtime persistent update and associated apparatus. The method enables BIOS uCode patches to be received during platform runtime operations and written to first and second uCode extension regions as uCode images for a firmware device layout that further includes a uCode base region in which a current uCode image is stored. Following a platform reset, the first and second uCode extension regions are inspected to determine if one or more valid and newer uCode images (than the current uCode image) are present. If so, the newest uCode image is booted rather than the current uCode image. Following a successful boot, the newest uCode image is copied to the uCode base region to sync-up the current uCode image to the newest version. In one aspect, received uCode images are written to the first and second uCode extension regions in an alternating manner to support roll-back.