Re: [PATCH v2 1/7] ethdev: support report register names and filter

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 2/5/2024 10:51 AM, Jie Hai wrote:
> This patch adds "filter" and "names" fields to "rte_dev_reg_info"
> structure. Names of registers in data fields can be reported and
> the registers can be filtered by their names.
> 
> For compatibility, the original API rte_eth_dev_get_reg_info()
> does not use the name and filter fields. The new API
> rte_eth_dev_get_reg_info_ext() is added to support reporting
> names and filtering by names. If the drivers does not report
> the names, set them to "offset_XXX".
> 
> Signed-off-by: Jie Hai <haijie1@huawei.com>
> ---
>  doc/guides/rel_notes/release_24_03.rst |  8 ++++++
>  lib/ethdev/rte_dev_info.h              | 11 ++++++++
>  lib/ethdev/rte_ethdev.c                | 36 ++++++++++++++++++++++++++
>  lib/ethdev/rte_ethdev.h                | 22 ++++++++++++++++
>  4 files changed, 77 insertions(+)
> 
> diff --git a/doc/guides/rel_notes/release_24_03.rst b/doc/guides/rel_notes/release_24_03.rst
> index 84d3144215c6..5d402341223a 100644
> --- a/doc/guides/rel_notes/release_24_03.rst
> +++ b/doc/guides/rel_notes/release_24_03.rst
> @@ -75,6 +75,11 @@ New Features
>    * Added support for Atomic Rules' TK242 packet-capture family of devices
>      with PCI IDs: ``0x1024, 0x1025, 0x1026``.
>  
> +* **Added support for dumping regiters with names and filter.**
>

s/regiters/registers/

> +
> +  * Added new API functions ``rte_eth_dev_get_reg_info_ext()`` to and filter
> +  * the registers by their names and get the information of registers(names,
> +  * values and other attributes).
>  

'*' makes a bullet, but above seems one sentences, if so please only
keep the first '*'.

>  Removed Items
>  -------------
> @@ -124,6 +129,9 @@ ABI Changes
>  
>  * No ABI change that would break compatibility with 23.11.
>  
> +* ethdev: Added ``filter`` and ``names`` fields to ``rte_dev_reg_info``
> +  structure for reporting names of regiters and filtering them by names.
> +
>  

This will break the ABI.

Think about a case, an application compiled with an old version of DPDK,
later same application started to use this version without re-compile,
application will send old version of 'struct rte_dev_reg_info', but new
version of DPDK will try to access or update new fields of the 'struct
rte_dev_reg_info'

One option is:
- to add a new 'struct rte_dev_reg_info_ext',
- 'rte_eth_dev_get_reg_info()' still uses old 'struct rte_dev_reg_info'
- 'get_reg()' dev_ops will use this new 'struct rte_dev_reg_info_ext'
- Add deprecation notice to update 'rte_eth_dev_get_reg_info()' to use
new struct in next LTS release


>  Known Issues
>  ------------
> diff --git a/lib/ethdev/rte_dev_info.h b/lib/ethdev/rte_dev_info.h
> index 67cf0ae52668..2f4541bd46c8 100644
> --- a/lib/ethdev/rte_dev_info.h
> +++ b/lib/ethdev/rte_dev_info.h
> @@ -11,6 +11,11 @@ extern "C" {
>  
>  #include <stdint.h>
>  
> +#define RTE_ETH_REG_NAME_SIZE 128
> +struct rte_eth_reg_name {
> +	char name[RTE_ETH_REG_NAME_SIZE];
> +};
> +
>  /*
>   * Placeholder for accessing device registers
>   */
> @@ -20,6 +25,12 @@ struct rte_dev_reg_info {
>  	uint32_t length; /**< Number of registers to fetch */
>  	uint32_t width; /**< Size of device register */
>  	uint32_t version; /**< Device version */
> +	/**
> +	 * Filter for target subset of registers.
> +	 * This field could affects register selection for data/length/names.
> +	 */
> +	char *filter;
> +	struct rte_eth_reg_name *names; /**< Registers name saver */
>  };
>  
>  /*
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> index f1c658f49e80..3e0294e49092 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -6388,8 +6388,39 @@ rte_eth_read_clock(uint16_t port_id, uint64_t *clock)
>  
>  int
>  rte_eth_dev_get_reg_info(uint16_t port_id, struct rte_dev_reg_info *info)
> +{
> +	struct rte_dev_reg_info reg_info;
> +	int ret;
> +
> +	if (info == NULL) {
> +		RTE_ETHDEV_LOG_LINE(ERR,
> +			"Cannot get ethdev port %u register info to NULL",
> +			port_id);
> +		return -EINVAL;
> +	}
> +
> +	reg_info.length = info->length;
> +	reg_info.data = info->data;
> +	reg_info.names = NULL;
> +	reg_info.filter = NULL;
> +
> +	ret = rte_eth_dev_get_reg_info_ext(port_id, &reg_info);
> +	if (ret != 0)
> +		return ret;
> +
> +	info->length = reg_info.length;
> +	info->width = reg_info.width;
> +	info->version = reg_info.version;
> +	info->offset = reg_info.offset;
> +
> +	return 0;
> +}
> +
> +int
> +rte_eth_dev_get_reg_info_ext(uint16_t port_id, struct rte_dev_reg_info *info)
>  {
>  	struct rte_eth_dev *dev;
> +	uint32_t i;
>  	int ret;
>  
>  	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> @@ -6408,6 +6439,11 @@ rte_eth_dev_get_reg_info(uint16_t port_id, struct rte_dev_reg_info *info)
>  
>  	rte_ethdev_trace_get_reg_info(port_id, info, ret);
>  
> +	/* Report the default names if drivers not report. */
> +	if (info->names != NULL && strlen(info->names[0].name) == 0)
> +		for (i = 0; i < info->length; i++)
> +			sprintf(info->names[i].name, "offset_%x",
> +				info->offset + i * info->width);
>

Better to use 'snprintf()'

>  	return ret;
>  }
>  
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
> index 2687c23fa6fb..3abc2ad3f865 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -5053,6 +5053,28 @@ __rte_experimental
>  int rte_eth_get_monitor_addr(uint16_t port_id, uint16_t queue_id,
>  		struct rte_power_monitor_cond *pmc);
>  
> +/**
> + * Retrieve the filtered device registers (values and names) and
> + * register attributes (number of registers and register size)
> + *
> + * @param port_id
> + *   The port identifier of the Ethernet device.
> + * @param info
> + *   Pointer to rte_dev_reg_info structure to fill in. If info->data is
> + *   NULL, the function fills in the width and length fields. If non-NULL,
> + *   the values of registers whose name contains the filter string are put
> + *   into the buffer pointed at by the data field. Do the same for the names
> + *   of registers if info->names is not NULL.
>

May be good to mention if info->names is not NULL, but driver doesn't
support names, ehtdev fills the names automatically.

As both 'rte_eth_dev_get_reg_info()' & 'rte_eth_dev_get_reg_info_ext()'
use same dev_ops ('get_reg()'), it is possible that driver doesn't
support filtering, so if the user provides info->filter but driver
doesn't support it, I think API should return error, what do you think?

And can you please make it clear above, if filtering is provided with
info->data = NULL, are the returned width and length fields for filtered
number of registers or all registers?


> + * @return
> + *   - (0) if successful.
> + *   - (-ENOTSUP) if hardware doesn't support.
> + *   - (-EINVAL) if bad parameter.
> + *   - (-ENODEV) if *port_id* invalid.
> + *   - (-EIO) if device is removed.
> + *   - others depends on the specific operations implementation.
> + */
> +int rte_eth_dev_get_reg_info_ext(uint16_t port_id, struct rte_dev_reg_info *info);
> +
>

Can you please make the new API as experimental. That is the requirement
for new APIs.

Also need to add the API to version.map


>  /**
>   * Retrieve device registers and register attributes (number of registers and
>   * register size)