Hello,
On 12/02/2014 07:52 AM, Jijiang Liu wrote:
> Replace the inner_l2_len and the inner_l3_len field with the outer_l2_len and
> outer_l3_len field, and rework csum forward engine and i40e PMD due to these
> changes.
>
> Signed-off-by: Jijiang Liu <jijiang.liu at intel.com>
[...]
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -276,8 +276,8 @@ struct rte_mbuf {
> uint64_t tso_segsz:16; /**< TCP TSO segment size */
>
> /* fields for TX offloading of tunnels */
> - uint64_t inner_l3_len:9; /**< inner L3 (IP) Hdr Length.
> */
> - uint64_t inner_l2_len:7; /**< inner L2 (MAC) Hdr
> Length. */
> + uint64_t outer_l3_len:9; /**< Outer L3 (IP) Hdr Length.
> */
> + uint64_t outer_l2_len:7; /**< Outer L2 (MAC) Hdr
> Length. */
>
> /* uint64_t unused:8; */
> };
Sorry for entering lately this discussion, but i'm not convinced by the
choice of outer_lx_len rather than inner_lx_len for new fields.
I agree with Olivier that new flags should only be related to the use of
new fields, to maintain coherency with oldest implementations.
But from a stack point of view, i think it is better to have lx_len
fields that target the outer layers, and to name new fields inner_lx_len.
Let's discuss the two possibilities.
1) outer_lx_len fields are introduced.
In this case, the stack should have knowledge that it is processing
tunneled packets to use outer_lx_len rather than lx_len,
or stack should always use outer_lx_len packet and move those fields to
lx_len packets if no tunneling occurs...
I think it will induce extra processing that does not seem to be really
needed.
2) inner_lx_len fields are introduced.
In this case, the stack first uses lx_len fields. When packet should be
tunneled, lx_len fields are moved to inner_lx_len fields.
Then the stack can process the outer layer and still use the lx_len fields.
For example:
an eth/IP/TCP forged packet will look like this:
Ether/IP/UDP/xxx
m->flags = IP_CKSUM
m->l2_len = sizeof(ether)
m->l3_len = sizeof(ip)
m->l4_len = sizeof(udp)
m->inner_l2_len = 0
m->inner_l3_len = 0
When entering tunnel for example a VXLAN interface, lx_len will be moved
to inner_lx_len
Ether/IP/UDP/xxx
m->flags = INNER_IP_CKSUM
m->l2_len = 0
m->l3_len = 0
m->l4_len = 0
m->inner_l2_len = sizeof(ether)
m->inner_l3_len = sizeof(ip)
once complete encapsulation is processed by the stack, the packet will
look like
Ether/IP/UDP/VXLAN/Ether/IP/UDP/xxx
m->flags = IP_CKSUM | INNER_IP_CKSUM
m->l2_len = sizeof(ether)
m->l3_len = sizeof(ip)
m->l4_len = sizeof(udp)
m->inner_l2_len = sizeof(ether) + sizeof (vxlan)
m->inner_l3_len = sizeof(ip)
didier
