config BLK bool "Support block devices" depends on DM default y if DM_MMC help Enable support for block devices, such as SCSI, MMC and USB flash sticks. These provide a block-level interface which permits reading, writing and (in some cases) erasing blocks. Block devices often have a partition table which allows the device to be partitioned into several areas, called 'partitions' in U-Boot. A filesystem can be placed in each partition. config SCSI bool "Support SCSI controllers" help This enables support for SCSI (Small Computer System Interface), a parallel interface widely used with storage peripherals such as hard drives and optical drives. The SCSI standards define physical interfaces as well as protocols for controlling devices and tranferring data. config DM_SCSI bool "Support SCSI controllers with driver model" depends on BLK help This option enables the SCSI (Small Computer System Interface) uclass which supports SCSI and SATA HDDs. For every device configuration (IDs/LUNs) a block device is created with RAW read/write and filesystem support. config BLOCK_CACHE bool "Use block device cache" default n help This option enables a disk-block cache for all block devices. This is most useful when accessing filesystems under U-Boot since it will prevent repeated reads from directory structures and other filesystem data structures. config IDE bool "Support IDE controllers" help Enables support for IDE (Integrated Drive Electronics) hard drives. This allows access to raw blocks and filesystems on an IDE drive from U-Boot. See also CMD_IDE which provides an 'ide' command for performing various IDE operations.