Hi Vladimir,

 

Currently, mem-to-mem dma transfers happen within a single process address space. This feature aims to extend support for transfers across multiple process address spaces to meet the requirements of inter-process or inter-VM networking. In environments where share memory is not feasible due to security concerns, this feature allows controlled software to use DMA for packet transfers as needed.

 

Regards.

 

From: Medvedkin, Vladimir <vladimir.medvedkin@intel.com>
Sent: Monday, July 14, 2025 3:47 PM
To: dev@dpdk.org
Cc: Bruce Richardson <bruce.richardson@intel.com>
Subject: [EXTERNAL] Re: [PATCH v0 1/1] doc: announce inter-device DMA capability support in dmadev

 

Hi Vamsi, Could you please tell us more about usecases for this feature? Thanks! On 7/10/2025 9: 51 AM, Vamsi Krishna wrote: > From: Vamsi Attunuru <vattunuru@ marvell. com> > > Modern DMA hardware supports data transfer between

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Hi Vamsi,
 
Could you please tell us more about usecases for this feature?
 
Thanks!
 
On 7/10/2025 9:51 AM, Vamsi Krishna wrote:
> From: Vamsi Attunuru <vattunuru@marvell.com>
> 
> Modern DMA hardware supports data transfer between multiple
> DMA devices, enabling data communication across isolated domains or
> containers. To facilitate this, the ``dmadev`` library requires changes
> to allow devices to register with or unregisters from DMA groups for
> inter-device communication. This feature is planned for inclusion
> in DPDK 25.11.
> 
> Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
> ---
>   doc/guides/rel_notes/deprecation.rst | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> index e2d4125308..46836244dd 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -152,3 +152,10 @@ Deprecation Notices
>   * bus/vmbus: Starting DPDK 25.11, all the vmbus API defined in
>     ``drivers/bus/vmbus/rte_bus_vmbus.h`` will become internal to DPDK.
>     Those API functions are used internally by DPDK core and netvsc PMD.
> +
> +* dmadev: a new capability flag ``RTE_DMA_CAPA_INTER_DEV`` will be added
> +  to advertise DMA device's inter-device DMA copy capability. To enable
> +  this functionality, a few dmadev APIs will be added to configure the DMA
> +  access groups, facilitating coordinated data communication between devices.
> +  A new ``dev_idx`` field will be added to the ``struct rte_dma_vchan_conf``
> +  structure to configure a vchan for data transfers between any two DMA devices.
 
-- 
Regards,
Vladimir