From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH] ethdev: add field for device data per process
Date: Wed, 03 Oct 2018 22:44:13 +0200
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References: <1538047596-23954-1-git-send-email-alejandro.lucero@netronome.com>
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To: Alejandro Lucero <alejandro.lucero@netronome.com>, ferruh.yigit@intel.com,
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+ Cc more people

27/09/2018 13:26, Alejandro Lucero:
> Primary and secondary processes share a per-device private data. With
> current design it is not possible to have data per-device per-process.
> This is required for handling properly the CPP interface inside the NFP
> PMD with multiprocess support.
> 
> There is also at least another PMD driver, tap, with similar
> requirements for per-process device data.

Yes, it is required to fix tap PMD for multi-process usage.

I am in favor of accepting this change in 18.11.

[...]
> @@ -539,7 +539,13 @@ struct rte_eth_dev {
>  	eth_rx_burst_t rx_pkt_burst; /**< Pointer to PMD receive function. */
>  	eth_tx_burst_t tx_pkt_burst; /**< Pointer to PMD transmit function. */
>  	eth_tx_prep_t tx_pkt_prepare; /**< Pointer to PMD transmit prepare function. */
> -	struct rte_eth_dev_data *data;  /**< Pointer to device data */
> +	/**
> +	 * Next two fields are per-device data but *data is shared between

All fields in rte_eth_dev are per-device.

> +	 * primary and secondary processes and *process_private is per-process
> +	 * private.
> +	 */
> +	struct rte_eth_dev_data *data;  /**< Pointer to device data. */
> +	void *process_private; /**< Pointer to per-process device data. */

We could explain here that this memory is allocated by the PMD.