Example 1:¶

Memory signature domain is configured for CRC32 every 512B block.

Wire signature domain is configured for no signature.

A SEND is issued using the MKEY as a local key.

Result: device will gather the data with the CRC32 fields from the MKEY (using whatever layout configured to the MKEY to locate the actual memory), validate each CRC32 against the previous 512 bytes of data, strip the CRC32 field, and transmit only 512 bytes of data to the wire.

Example 1.1:¶

Same as above, but a RECV is issued with the same key, and RX happens.

Result: device will receive the data from the wire, scatter it to the MKEY (using whatever layout configured to the MKEY to locate the actual memory), generating and scattering additional CRC32 field after every 512 bytes that are scattered.

Example 2:¶

Memory signature domain is configured for no signature.

Wire signature domain is configured for T10DIF every 4K block.

The MKEY is sent to a remote node that issues a RDMA_READ to this MKEY.

Result: device will gather the data from the MKEY (using whatever layout configured to the MKEY to locate the actual memory), transmit it to the wire while generating an additional T10DIF field every 4K of data.

Example 2.1:¶

Same as above, but remote node issues a RDMA_WRITE to this MKEY.

Result: Device will receive the data from the wire, validate each T10DIF field against the previous 4K of data, strip the T10DIF field, and scatter the data alone to the MKEY (using whatever layout configured to the MKEY to locate the actual memory).

Block signature attributes¶

Block signature attributes describe the input and output data structures in memory and wire domains.

struct mlx5dv_sig_block_attr {


    const struct mlx5dv_sig_block_domain *mem;


    const struct mlx5dv_sig_block_domain *wire;


    uint32_t flags;


    uint8_t check_mask;


    uint8_t copy_mask;


    uint64_t comp_mask;
};
    

mem

A pointer to the signature configuration for the memory domain or NULL if the domain does not have a signature.

wire

A pointer to the signature configuration for the wire domain or NULL if the domain does not have a signature.

flags

A bitwise OR of the various values described below.

check_mask

Each bit of check_mask corresponds to a byte of the signature field in input domain. Byte of the input signature is checked if corresponding bit in check_mask is set. Bits not relevant to the signature type are ignored.

copy_mask

A mask to specify what part of the signature is copied from the source domain to the destination domain. The copy mask is usually calculated automatically. The signature is copied if the same signature type is configurted on both domains. The parts of the T10-DIF are compared and handled independetly.

comp_mask

Reserved for future extension, must be 0 now.

Block signature domain¶

struct mlx5dv_sig_block_domain {


    enum mlx5dv_sig_type sig_type;


    union {


        const struct mlx5dv_sig_t10dif *dif;


        const struct mlx5dv_sig_crc *crc;


    } sig;


    enum mlx5dv_block_size block_size;


    uint64_t comp_mask;
};
    

sig_type

The signature type for this domain, one of the following

sig

Depending on sig_type, this is the per signature type specific configuration.

block_size

The block size for this domain, one of enum mlx5dv_sig_block_size.

comp_mask

Reserved for future extension, must be 0 now.

CRC signature¶

struct mlx5dv_sig_crc {


    enum mlx5dv_sig_crc_type type;


    uint64_t seed;
};
    

type

The specific CRC type, one of the following.

seed

A seed for the CRC calculation per block. Bits not relevant to the CRC type are ignored. For example, all bits are used for CRC64_XP10, but only the 32 least significant bits are used for CRC32/CRC32C.

T10DIF signature¶

T10DIF signature is defined in the T10 specifications (T10 SBC-3) for block-level data protection. The size of data block protected by T10DIF must be modulo 8bytes as required in the T10DIF specifications. Note that when setting the initial LBA value to ref_tag, it should be the value of the first block to be transmitted.

struct mlx5dv_sig_t10dif {


    enum mlx5dv_sig_t10dif_bg_type bg_type;


    uint16_t bg;


    uint16_t app_tag;


    uint32_t ref_tag;


    uint16_t flags;
};
    

bg_type

The block guard type to be used, one of the following.

bg

A seed for the block guard calculation per block.

app_tag

An application tag to generate or validate.

ref_tag

A reference tag to generate or validate.

flags

Flags for the T10DIF attributes, one of the following.