On 2/2/2023 5:16 PM, Thomas Monjalon wrote:
> 02/02/2023 13:44, Ferruh Yigit:
>> --- a/lib/net/rte_gre.h
>> +++ b/lib/net/rte_gre.h
>> @@ -28,6 +28,8 @@ extern "C" {
>> */
>> __extension__
>> struct rte_gre_hdr {
>> + union {
>> + struct {
>> #if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
>> uint16_t res2:4; /**< Reserved */
>> uint16_t s:1; /**< Sequence Number Present bit */
>> @@ -45,6 +47,9 @@ struct rte_gre_hdr {
>> uint16_t res3:5; /**< Reserved */
>> uint16_t ver:3; /**< Version Number */
>> #endif
>> + };
>> + rte_be16_t c_rsvd0_ver;
>> + };
>> uint16_t proto; /**< Protocol Type */
>
> Why adding an unioned field c_rsvd0_ver?
>
>
Because existing usage in the drivers require to access these fields as
a single 16 bytes variable.
like mlx was using it as:
`X(SET_BE16, gre_c_ver, v->c_rsvd0_ver, rte_flow_item_gre) \`
When all usage switched to flow item specific fields to generic headers,
there needs a way to represent this in the generic header.
By adding 'c_rsvd0_ver' to generic header it becomes:
`X(SET_BE16, gre_c_ver, v->hdr.c_rsvd0_ver, rte_flow_item_gre) \`
Or another sample, previous version of code was updated as following:
`
- size = sizeof(((struct rte_flow_item_gre *)NULL)->c_rsvd0_ver);
+ size = sizeof(((struct rte_flow_item_gre *)NULL)->hdr.proto);
`
Because generic field to represent 'c_rsvd0_ver' is missing, 'hdr.proto'
was used, this was wrong.
Although the sizes of fields are same and functionally works, they are
different fields, this is worse than sizeof(uint16_t);
Another usage in testpmd:
`
[ITEM_GRE_C_RSVD0_VER] = {
.name = "c_rsvd0_ver",
@@ -4082,7 +4082,7 @@ static const struct token token_list[] = {
.next = NEXT(item_gre, NEXT_ENTRY(COMMON_UNSIGNED),
item_param),
.args = ARGS(ARGS_ENTRY_HTON(struct rte_flow_item_gre,
- c_rsvd0_ver)),
+ hdr.c_rsvd0_ver)),
`
But looking it again perhaps it can be named differently, because it is
not a reserved field in the generic header, though I am not sure what
can be a good variable name.
