sda - SD/MMC architecture
The sda module provides support services for Secure Digital (SD) and MultiMediaCard (MMC) slot and card device drivers.
64-bit ELF kernel module (x86)
See attributes(5) for a description of the following attributes:
The sda module provides support only for SD/MMC devices that are connected via a supported slot driver. Notably, slots that are on USB busses are normally treated as USB mass storage devices and are serviced by the scsa2usb(7D) driver.