fuchsia.hardware.block

Transmitted in the block_fifo_response_t.

Only used if opcode & BLOCK_GROUP_ITEM.

Only valid if transmitted in request.

The number of messages in the transaction completed by the block server.

The number of blocks in this block device.

The size of a single block.

Max size in bytes per transfer. May be BLOCK_MAX_TRANSFER_UNBOUNDED if there is no restriction.

The number of blocks in this block device.

The size of a single block.

The maximum size, in bytes, of a transfer. Set to MAX_TRANSFER_UNBOUNDED if no such maximum exists.

Identifiers about the device; refer to the "FLAG_*" documentation above.

Command and flags.

Available for temporary use.

VMO of data to read or write.

Transfer length in blocks (0 is invalid).

Device offset in blocks.

VMO offset in blocks.

Total number of block ops processed

Total number of blocks processed

The stats about read from the device.

The stats about write to the device.

The stats about trim commands.

The stats about flush commands.

The stats about barrier before commands.

The stats about barrier after commands.

Command and flags.

Transfer length in blocks (0 is invalid).

Device offset in blocks.

All Commands

Read and Write ops use rw for parameters.

Block device has bootdata partition map provided by device metadata.

Flag advertising trim support.

Require that this operation complete before any subsequent operations are started.

Prevents later operations from being reordered before this one.

Require that this operation will not begin until all previous operations have completed.

Prevents earlier operations from being reordered after this one.

Mark this operation as "Force Unit Access" (FUA), indicating that it should not complete until the data is written to the non-volatile medium (write), and that reads should bypass any on-device caches.

Associate the following request with |group|.

Only respond after this request (and all previous within group) have completed. Only valid with BLOCKIO_GROUP_ITEM.

Detaches the VMO from the block device.

Write any controller or device cached data to nonvolatile storage. This operation always implies BARRIER_BEFORE and BARRIER_AFTER, meaning that previous operations will complete before it starts and later operations will not start until it is done.

Performs a regular data read or write from the device. The operation may be cached internally.

Instructs the device to invalidate a number of blocks, making them usable for storing something else. This is basically a "delete" optimization, where the device is in charge of discarding the old content without clients having to write a given pattern. The operation may be cached internally.

The device has a bootdata partition map.

All writes to the block device will fail.

The block device may be removed from the device during operation.

The device provides trim support.

The maximum value for a transfer size, identifying that there effectively exists no maximum for a single operation.

Multiple Block IO operations may be sent at once before a response is actually sent back. Block IO ops may be sent concurrently to different vmoids, and they also may be sent to different groups at any point in time.

MAX_TXN_GROUP_COUNT "groups" are pre-allocated lanes separated on the block server. Using a group allows multiple message to be buffered at once on a single communication channel before receiving a response.

Usage of groups is identified by BLOCKIO_GROUP_ITEM, and is optional.

These groups may be referred to with a "groupid", in the range [0, MAX_TXN_GROUP_COUNT).

The protocol to communicate with a single group is as follows:

1. SEND [N - 1] messages with an allocated groupid for any value of 1 <= N. The BLOCKIO_GROUP_ITEM flag is set for these messages.
2. SEND a final Nth message with the same groupid. The BLOCKIO_GROUP_ITEM | BLOCKIO_GROUP_LAST flags are set for this message.
3. RECEIVE a single response from the Block IO server after all N requests have completed. This response is sent once all operations either complete or a single operation fails. At this point, step (1) may begin again for the same groupid.

For BLOCKIO_READ and BLOCKIO_WRITE, N may be greater than 1. Otherwise, N == 1 (skipping step (1) in the protocol above).

Notes:

• groupids may operate on any number of vmoids at once.
• If additional requests are sent on the same groupid before step (3) has completed, then the additional request will not be processed. If BLOCKIO_GROUP_LAST is set, an error will be returned. Otherwise, the request will be silently dropped.
• Messages within a group are not guaranteed to be processed in any order relative to each other.
• All requests receive responses, except for ones with BLOCKIO_GROUP_ITEM that do not have BLOCKIO_GROUP_LAST set.

For example, the following is a valid sequence of transactions: -> (groupid = 1, vmoid = 1, OP = Write | GroupItem, reqid = 1) -> (groupid = 1, vmoid = 2, OP = Write | GroupItem, reqid = 2) -> (groupid = 2, vmoid = 3, OP = Write | GroupItem | GroupLast, reqid = 0) <- Response sent to groupid = 2, reqid = 0 -> (groupid = 1, vmoid = 1, OP = Read | GroupItem | GroupLast, reqid = 3) <- Response sent to groupid = 1, reqid = 3 -> (groupid = 3, vmoid = 1, OP = Write | GroupItem, reqid = 4) -> (groupid = don't care, vmoid = 1, OP = Read, reqid = 5) <- Response sent to reqid = 5 -> (groupid = 3, vmoid = 1, OP = Read | GroupItem | GroupLast, reqid = 6) <- Response sent to groupid = 3, reqid = 6

Each transaction reads or writes up to 'length' blocks from the device, starting at 'dev_offset' blocks, into the VMO associated with 'vmoid', starting at 'vmo_offset' blocks. If the transaction is out of range, for example if 'length' is too large or if 'dev_offset' is beyond the end of the device, ZX_ERR_OUT_OF_RANGE is returned.

Value reserved for "invalid" VmoId. Will never be allocated by the server, and may be utilized as a local value for an unallocated ID.

The Request ID allowing callers to correspond requests with responses. This field is entirely for client-side bookkeeping; there is no obligation to make request IDs unique.