RE: [EXTERNAL] Re: [PATCH v0 1/1] doc: announce inter-device DMA capability support in dmadev

[Vamsi Krishna Attunuru <vattunuru@marvell.com>]

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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<mailto: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<mailto: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



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