Block devices

Storage read and written in fixed-size sectors, such as a ramdisk. More...

Collaboration diagram for Block devices:

Data Structures
struct	block_ops_t
	Operations a block driver provides; every one is required. More...
struct	block_device_t
	A block device: driver operations bound to one device instance. More...

Macros
#define	BLOCK_SECTOR_SIZE   512U
	Sector size of every block device, in bytes.

Detailed Description

Storage read and written in fixed-size sectors, such as a ramdisk.

Block devices have no VFS node. The device description's mounts section attaches a filesystem to one; the generated code builds the block_device_t from the driver's <driver>_block_ops and device instance. Operations return 0 on success and -1 with errno set on failure, and are called only from thread context, never from interrupt handlers.

A block driver sets block: true in its binding. Transfers are whole BLOCK_SECTOR_SIZE sectors; a sector range outside the device fails with EIO. There is no erase operation: current devices overwrite in place.

Driver	Compatible	Backing store
Ramdisk	homecore,ramdisk	A .bss buffer sized by the size property; lost on reset

See also

Files and storage for how Filesystems use Block devices devices.

Block devices for the Drivers, their configuration, and tests.