Re: [dpdk-dev] [PATCH v2 1/5] ethdev: update modify field flow action

[Ori Kam <orika@nvidia.com>]

Hi Slava,

> -----Original Message-----
> From: Slava Ovsiienko <viacheslavo@nvidia.com>
> Sent: Monday, October 11, 2021 2:46 AM
> Subject: [PATCH v2 1/5] ethdev: update modify field flow action
> 
> The generic modify field flow action introduced in [1] has some issues related to the immediate source
> operand:
> 
>   - immediate source can be presented either as an unsigned
>     64-bit integer or pointer to data pattern in memory.
>     There was no explicit pointer field defined in the union.
> 
>   - the byte ordering for 64-bit integer was not specified.
>     Many fields have shorter lengths and byte ordering
>     is crucial.
> 
>   - how the bit offset is applied to the immediate source
>     field was not defined and documented.
> 
>   - 64-bit integer size is not enough to provide IPv6
>     addresses.
> 
> In order to cover the issues and exclude any ambiguities the following is done:
> 
>   - introduce the explicit pointer field
>     in rte_flow_action_modify_data structure
> 
>   - replace the 64-bit unsigned integer with 16-byte array
> 
>   - update the modify field flow action documentation
> 
> [1] commit 73b68f4c54a0 ("ethdev: introduce generic modify flow action")
> 
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
> ---
>  doc/guides/prog_guide/rte_flow.rst     | 16 ++++++++++++++++
>  doc/guides/rel_notes/release_21_11.rst |  9 +++++++++
>  lib/ethdev/rte_flow.h                  | 17 ++++++++++++++---
>  3 files changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
> index 2b42d5ec8c..1ceecb399f 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -2835,6 +2835,22 @@ a packet to any other part of it.
>  ``value`` sets an immediate value to be used as a source or points to a  location of the value in memory. It
> is used instead of ``level`` and ``offset``  for ``RTE_FLOW_FIELD_VALUE`` and
> ``RTE_FLOW_FIELD_POINTER`` respectively.
> +The data in memory should be presented exactly in the same byte order
> +and length as in the relevant flow item, i.e. data for field with type
> +RTE_FLOW_FIELD_MAC_DST should follow the conventions of dst field in
> +rte_flow_item_eth structure, with type RTE_FLOW_FIELD_IPV6_SRC -
> +rte_flow_item_ipv6 conventions, and so on. If the field size is large
> +than
> +16 bytes the pattern can be provided as pointer only.
> +
> +The bitfield extracted from the memory being applied as second
> +operation parameter is defined by action width and by the destination field offset.
> +Application should provide the data in immediate value memory (either
> +as buffer or by pointer) exactly as item field without any applied
> +explicit offset, and destination packet field (with specified width and
> +bit offset) will be replaced by immediate source bits from the same bit
> +offset. For example, to replace the third byte of MAC address with
> +value 0x85, application should specify destination width as 8,
> +destination width as 16, and provide immediate value as sequence of bytes {xxx, xxx, 0x85, xxx, xxx, xxx}.
> 

I think you have a typo destination width as 16 should be destination offset as 16.
If fixed you can add my ack to the next version.

Best,
Ori