[dpdk-dev] [PATCH v3 01/25] ethdev: introduce generic flow API

[Adrien Mazarguil]

Hi Wei,

On Tue, May 23, 2017 at 06:07:20AM +0000, Zhao1, Wei wrote:
> Hi,  Adrien
> 
> > +struct rte_flow_item_raw {
> > +	uint32_t relative:1; /**< Look for pattern after the previous item. */
> > +	uint32_t search:1; /**< Search pattern from offset (see also limit). */
> > +	uint32_t reserved:30; /**< Reserved, must be set to zero. */
> > +	int32_t offset; /**< Absolute or relative offset for pattern. */
> > +	uint16_t limit; /**< Search area limit for start of pattern. */
> > +	uint16_t length; /**< Pattern length. */
> > +	uint8_t pattern[]; /**< Byte string to look for. */ };
> 
> When I use this API to test igb flex filter, I find that 
> in the struct rte_flow_item_raw, the member  pattern is not the same as my purpose.
> For example, If I type in  " flow create 0 ingress pattern raw relative is 0 pattern is 0123  / end actions queue index 1 / end "
> What I get in NIC layer is  pattern[]={ 0x30, 0x31, 0x32, 0x33, 0x0 <repeats 124 times> }.
> But what I need is pattern[]={0x01, 0x23, 0x0 <repeats 126 times>}

Similar limitation as I answered in [1] then. This is not a problem in the
rte_flow API, it's only that the testpmd parser currently provides
unprocessed strings to the PMD, and there is currently no method to work
around that.

> About the format change of flex_filter, I have reference to the testpmd function cmd_flex_filter_parsed(),
> There is details of format change from ASIC code to data, for example:
> 
>             for (i = 0; i < len; i++) {
>                         c = bytes_ptr[i];
>                         if (isxdigit(c) == 0) {
>                                     /* invalid characters. */
>                                     printf("invalid input\n");
>                                     return;
>                         }
>                         val = xdigit2val(c);
>                         if (i % 2) {
>                                     byte |= val;
>                                     filter.bytes[j] = byte;
>                                     printf("bytes[%d]:%02x ", j, filter.bytes[j]);
>                                     j++;
>                                     byte = 0;
>                         } else
>                                     byte |= val << 4;
>             }  
> 
> and there is also usage example in the DPDK document testpmd_app_ug-16.11.pdf:
> (it also not use ASIC code)
> 
> testpmd> flex_filter 0 add len 16 bytes 0x00000000000000000000000008060000 \
> mask 000C priority 3 queue 3

I understand, the difference between both commands is only that unlike
flex_filter, flow does not interpret the provided string as hexadecimal.

> so, will our new generic flow API align to the old format in flex byte filter in 17.08 or in the future?

What I have in mind instead is a printf-like input method. Using the rule
you provided above:

 flow create 0 ingress pattern raw relative is 0 pattern is 0123  / end actions queue index 1 / end

Will always yield "0123", however:

 flow create 0 ingress pattern raw relative is 0 pattern is \x00\x01\x02\x03  / end actions queue index 1 / end

Will yield the intended pattern. Currently this format is interpreted as is
(you'll get "\x00\x01\x02\x03") however escape interpretation is in the
plans.

> At least in the struct rte_flow_item_raw, the member  pattern is the same as old filter?

It is the same as the old filter, except you cannot provide it in
hexadecimal format yet. No changes needed on the PMD side in any case.

Again, this is only a testpmd implementation issue, that doesn't prevent
developers from creating programs that directly provide binary data to RAW
items, there's no such limitation.

[1] http://dpdk.org/ml/archives/dev/2017-May/065798.html

-- 
Adrien Mazarguil
6WIND