nx_config_query() subroutine

The structure of the data in the memory buffer is accelerator type-dependent but always starts with the following common structure:

struct nx_config_com {
        uint32_t  ncc_version;           /* version number                    */
        uint32_t  ncc_res1;              /* Reserved - padding                */
        uint64_t  ncc_gencount;          /* Generation count                  */
#ifdef __64BIT__
        nx_accel_unit_t *ncc_accel_buf_addr; /* unit info array address       */
#else
        uint32_t  ncc_res2;              /* Not used - must be 0              */
        nx_accel_unit_t *ncc_accel_buf_addr; /* unit info array address       */
#endif
        uint32_t  ncc_accel_buf_size;    /* unit info array size in bytes     */
        uint32_t  ncc_avail_for_use_credits; /* Total number of credits the   *
                                              * caller can potentially access *
                                              * to send work to the accel.    */
        uint32_t  ncc_avail_for_res_credits; /* Max number of credits the     *
                                              * caller can reserve for        *
                                              * exclusive use.                *
                                              * (0 for non-privileged callers)*/
        uint32_t  ncc_total_num_units;   /* Total number of accelerator units */
        uint32_t  ncc_num_units_in_buf;  /* # of units described in buffer    */
        uint32_t  ncc_res3[17];          /* Reserved for future extension     */
};

For GZIP accelerator, this structure is embedded into a GZIP-specific data structure:

typedef struct nx_gzip_config {
        struct nx_config_com ngc_com;       /* Common with other accel types  */
#define NX_GZIP_CONFIG_VER0     0x455A0000
#define NX_GZIP_CONFIG_VER      NX_GZIP_CONFIG_VER0
        uint64_t  ngc_max_processed_bytes;  /* Max number of bytes processed  *
                                             * per request                    */
        uint64_t  ngc_comp_rec_min_bytes;   /* Compress Recommended Min Bytes */
        uint64_t  ngc_decomp_rec_min_bytes; /* Decompress Recomm. Min Bytes   */
        uint64_t  ngc_res1[8];              /* Reserved for future extensions */
} nx_gzip_config_t;

The <sys/nx.h> header file defines the following fields to facilitate access to the ngc_com structure that is embedded in the nx_gzip_config structure:

#define ngc_version                     ngc_com.ncc_version
#define ngc_gencount                    ngc_com.ncc_gencount
#define ngc_accel_buf_addr              ngc_com.ncc_accel_buf_addr
#define ngc_accel_buf_size              ngc_com.ncc_accel_buf_size
#define ngc_total_num_units             ngc_com.ncc_total_num_units
#define ngc_num_units_in_buf            ngc_com.ncc_num_units_in_buf
#define ngc_avail_for_use_credits       ngc_com.ncc_avail_for_use_credits
#define ngc_avail_for_res_credits       ngc_com.ncc_avail_for_res_credits

The application thread must initialize the ngc_gencount, ngc_accel_buf_addr, and ngc_accel_buf_size fields in the following ways:

• The ngc_gencount field must be set to 0 or to the value returned by a previous call to the nx_config_query subroutine.
• The ngc_accel_buf_addr field must be set to NULL or the effective address of a memory buffer.
• The ngc_accel_buf_size field must be set to 0 or the size of the memory buffer that is referenced by the ngc_accel_buf_addr field.

If the generation count value that is passed to the ngc_gencount field matches the current value of the generation count in the nx_gzip_gen_count() macro output for a specific type of accelerator, it indicates that the configuration data has not changed since the last call to the nx_config_query subroutine. In this case, the nx_config_query subroutine returns 1 and the configuration data is not copied into the memory buffer that is referenced by the buf_address variable. If the generation count value that is passed to the ngc_gencount field does not match the current value of generation count, it indicates that the configuration settings have changed since the last call to the nx_config_query subroutine. In this case, the nx_config_query subroutine copies the current configuration data into the memory buffer that is referenced by the buf_address variable.

If the ngc_accel_buf_addr or ngc_accel_buf_size fields are set to 0, the configuration data for each accelerator unit is not returned. Otherwise, the configuration data for each accelerator unit is returned in an array of nx_accel_unit_t structures at the address that is passed to the ngc_accel_buf_addr field. The nx_accel_unit_t structure is listed as follows:

typedef struct nx_accel_unit {
        nx_unit_id_t  na_id;                /* HW accelerator unit ID         */
        uint32_t  na_sradid;                /* Accelerator unit's SRAD ID     */
        uint32_t  na_avail_for_use_credits; /* Total number of credits the    *
                                             * caller can potentially access  *
                                             * to send work to the accel unit */
        uint32_t  na_avail_for_res_credits; /* Max number of credits the      *
                                             * caller can reserve for         *
                                             * exclusive use on this unit     *
                                             * (0 for non-privileged callers) */
        uint32_t  na_res1[3];               /* reserved                       */
} nx_accel_unit_t;

The ngc_num_units_in_buf field contains the number of elements in the accelerator unit array. This number can be less than the ngc_total_num_units value if the ngc_accel_buf_size value is not sufficient for all the data.