Provide block layer support for the kernel.

Disable this option to remove the block layer support from the
kernel. This may be useful for embedded devices.

If this option is disabled:

- block device files will become unusable
- some filesystems (such as ext3) will become unavailable.

Also, SCSI character devices and USB storage will be disabled since
they make use of various block layer definitions and facilities.

Say Y here unless you know you really don't want to mount disks and
suchlike.

source code:

block/partitions/core.c