Hi Somnath,
On Fri, Feb 07, 2020 at 07:13:04PM +0530, Somnath Kotur wrote:
> Olivier,
>
> On Thu, Feb 6, 2020 at 10:55 PM Olivier Matz <olivier.m...@6wind.com> wrote:
> >
> > Hi Somnath,
> >
> > Sorry for the delay, please find some comments below.
> >
> > I suggest the following title instead:
> >
> > mbuf: extend meaning of QinQ stripped bit
> >
> > On Mon, Jan 06, 2020 at 02:04:23PM +0530, Somnath Kotur wrote:
> > > Certain hardware may be able to strip and/or save only the outermost
> > > VLAN instead of both the VLANs in the mbuf in a QinQ scenario.
> > > To handle such cases, we could re-interpret setting of just
> > > PKT_RX_QINQ_STRIPPED to indicate that only the outermost VLAN has
> > > been stripped and saved in mbuf->vlan_tci_outer.
> >
> > To be sure we're on the same page: we are talking about case 7 of this
> > link: http://inbox.dpdk.org/dev/20191227145041.GQ22738@platinum/
>
> I'm not sure we are on the same page then, please see my response inline below
> >
> > So, even if the inner vlan_tci is not stripped from packet data, it has
> > to be saved in m->vlan_tci, because it is implied by PKT_RX_VLAN.
> >
> > From the same link, the case where the driver only strips+saves the
> > outer vlan without saving or stripping the inner one is case 3.
> >
> While this is how it works currently, I'm wondering how will the
> application know if this was
> a double VLAN pkt, correct?
If the hardware supports it and configured for it, the flag PKT_RX_QINQ
is set when there are 2 vlans.
FYI, the m->packet_type field can also be useful. It describes what is
really present in the packet data, as described in rte_mbuf_core.h:
/*
* The packet type, which is the combination of outer/inner L2, L3, L4
* and tunnel types. The packet_type is about data really present in the
* mbuf. Example: if vlan stripping is enabled, a received vlan packet
* would have RTE_PTYPE_L2_ETHER and not RTE_PTYPE_L2_VLAN because the
* vlan is stripped from the data.
*/
> Also when i look at options 5 and 7 I don't really see the difference
> in semantics between them ?
> Both seem to store the outer-vlan and inner-vlan in m->vlan_tci_outer
> and m->vlan_tci_inner respectively
>
> 7/ PKT_RX_VLAN | PKT_RX_QINQ | PKT_RX_QINQ_STRIPPED
> outer-vlan is removed from packet data
> m->vlan_tci_outer=outer-vlan
> m->vlan_tci=inner-vlan
The difference is about what was stripped or not from mbuf data.
> I was hoping that with the new interpretation of PKT_RX_QINQ_STRIPPED,
> it only meant that outer-vlan is removed from packet data
> and m->vlan_tci_outer = outer_vlan, while PKT_RX_QINQ implies it is a
> double-vlan pkt and PKT_RX_VLAN implies that pkt has VLAN
> associated with it? Not m->vlan_tci = inner-vlan
The meaning of each flag should be as simple as possible, I think we can
summarize them like this:
- PKT_RX_VLAN: the vlan is saved in vlan tci.
- PKT_RX_VLAN_STRIPPED: the vlan hdr is removed from packet data.
- PKT_RX_QINQ: the outer vlan is saved in vlan tci.
- PKT_RX_QINQ_STRIPPED: the inner vlan is stripped from packet data.
- When PKT_RX_QINQ is set, PKT_RX_VLAN* refer to the inner vlan
of initial packet, else it refers to the first vlan of the packet.
There is a link between vlan flag and vlan_tci field, and qinq flag and
vlan_tci_outer field.
I'm still not sure to understand what you expect. Can you give an
example with flags (which are set), and the expected content of m->vlan_tci
and m->vlan_tci_outer?
By the way, the case 5/ is not very well described too, maybe we should
add something about it.
Thanks,
Olivier
>
> Thanks
> Som
>
>
> > > Only When both PKT_RX_QINQ_STRIPPED and PKT_RX_VLAN_STRIPPED are set, the
> > > 2
> > > VLANs have been stripped by the hardware and their TCI are saved in
> > > mbuf->vlan_tci (inner) and mbuf->vlan_tci_outer (outer).
> > >
> > > Signed-off-by: Somnath Kotur <somnath.ko...@broadcom.com>
> > > ---
> > > lib/librte_mbuf/rte_mbuf_core.h | 15 +++++++++++----
> > > 1 file changed, 11 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/lib/librte_mbuf/rte_mbuf_core.h
> > > b/lib/librte_mbuf/rte_mbuf_core.h
> > > index 9a8557d..db1070b 100644
> > > --- a/lib/librte_mbuf/rte_mbuf_core.h
> > > +++ b/lib/librte_mbuf/rte_mbuf_core.h
> > > @@ -124,12 +124,19 @@
> > > #define PKT_RX_FDIR_FLX (1ULL << 14)
> > >
> > > /**
> > > - * The 2 vlans have been stripped by the hardware and their tci are
> > > - * saved in mbuf->vlan_tci (inner) and mbuf->vlan_tci_outer (outer).
> > > + * The outer vlan has been stripped by the hardware and their tci are
> > > + * saved in mbuf->vlan_tci_outer (outer).
> >
> > their tci are -> its tci is
> >
> > > * This can only happen if vlan stripping is enabled in the RX
> > > * configuration of the PMD.
> > > - * When PKT_RX_QINQ_STRIPPED is set, the flags (PKT_RX_VLAN |
> > > - * PKT_RX_VLAN_STRIPPED | PKT_RX_QINQ) must also be set.
> > > + * When PKT_RX_QINQ_STRIPPED is set, the flags (PKT_RX_VLAN |
> > > PKT_RX_QINQ)
> > > + * must also be set.
> >
> > ok
> >
> > > + * When both PKT_RX_QINQ_STRIPPED and PKT_RX_VLAN_STRIPPED are set, the
> > > 2 vlans
> > > + * have been stripped by the hardware and their tci are saved in
> > > + * mbuf->vlan_tci (inner) and mbuf->vlan_tci_outer (outer).
> >
> > This is correct, but I'd use a bullet list to add another sentence:
> >
> > * - If both PKT_RX_QINQ_STRIPPED and PKT_RX_VLAN_STRIPPED are set, the 2
> > vlans
> > * have been stripped by the hardware and their tci are saved in
> > * mbuf->vlan_tci (inner) and mbuf->vlan_tci_outer (outer).
> > * - If PKT_RX_QINQ_STRIPPED is set and PKT_RX_VLAN_STRIPPED is unset, only
> > the
> > * outer vlan is removed from packet data, but both tci are saved in
> > * mbuf->vlan_tci (inner) and mbuf->vlan_tci_outer (outer).
> >
> > > + * This can only happen if vlan stripping is enabled in the RX
> > > configuration
> > > + * of the PMD.
> >
> > The same exact sentence is above, this one can be removed.
> >
> > > + * When PKT_RX_QINQ_STRIPPED and PKT_RX_VLAN_STRIPPED are set,
> > > + * (PKT_RX_VLAN | PKT_RX_QINQ) must also be set.
> >
> > This can be removed too as it is redundant with above sentence:
> >
> > * When PKT_RX_QINQ_STRIPPED is set, the flags (PKT_RX_VLAN | PKT_RX_QINQ)
> > * must also be set.
> >
> >
> > Thanks,
> > Olivier
