Re: [dpdk-dev] [dpdk-dev, 2/3] eth_dev: add support for device dma mask

[Jan Viktorin <viktorin@rehivetech.com>]

Hello Alejandro,

On Thu, 12 May 2016 15:33:59 +0100
"Alejandro.Lucero" <alejandro.lucero@netronome.com> wrote:

> - New dma_mask field in rte_eth_dev_data.
>  - If PMD sets device dma_mask, call to check hugepages within

I think that one of the purposes of DPDK is to support DMA transfers
in userspace. In other words, I can see no reason to support dma_mask
at the ethdev level only.

We should consider adding this to the generic struct rte_device
(currently rte_pci_device). Thomas?

>    supported range.

I think, the '-' is unnecessary at the beginning of line. As for me
I prefer a fluent text describing the purpose. The '-' is useful for
a real list of notes.

> 
> Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>
> 
> ---
> lib/librte_ether/rte_ethdev.c | 7 +++++++
>  lib/librte_ether/rte_ethdev.h | 1 +
>  2 files changed, 8 insertions(+)
> 
> diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
> index a31018e..c0de88a 100644
> --- a/lib/librte_ether/rte_ethdev.c
> +++ b/lib/librte_ether/rte_ethdev.c
> @@ -280,9 +280,16 @@ rte_eth_dev_init(struct rte_pci_driver *pci_drv,
>  
>  	/* Invoke PMD device initialization function */
>  	diag = (*eth_drv->eth_dev_init)(eth_dev);
> +	if (diag)
> +		goto err;
> +
> +	if (eth_dev->data->dma_mask)
> +		diag = rte_eal_hugepage_check_address_mask(eth_dev->data->dma_mask);
> +

I don't understand what happens if the memory is out of the DMA mask. What can the driver
do? Does it just fail?

I think that this should be considered during a malloc instead. (Well, there is probably
no suitable API for this at the moment.)

Regards
Jan

>  	if (diag == 0)
>  		return 0;
>  
> +err:
>  	RTE_PMD_DEBUG_TRACE("driver %s: eth_dev_init(vendor_id=0x%u device_id=0x%x) failed\n",
>  			pci_drv->name,
>  			(unsigned) pci_dev->id.vendor_id,
> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index 2757510..34daa92 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -1675,6 +1675,7 @@ struct rte_eth_dev_data {
>  	enum rte_kernel_driver kdrv;    /**< Kernel driver passthrough */
>  	int numa_node;  /**< NUMA node connection */
>  	const char *drv_name;   /**< Driver name */
> +	uint64_t dma_mask; /** device supported address space range */
>  };
>  
>  /** Device supports hotplug detach */



-- 
   Jan Viktorin                  E-mail: Viktorin@RehiveTech.com
   System Architect              Web:    www.RehiveTech.com
   RehiveTech
   Brno, Czech Republic