[dpdk-dev] [EXT] Re: [PATCH 00/15] Octeon Tx/Tx2 Endpoint pmd

[Jerin Jacob]

On Wed, Jan 6, 2021 at 7:54 PM Ferruh Yigit <ferruh.yigit at intel.com> wrote:
>
> On 1/6/2021 11:58 AM, Jerin Jacob wrote:
> > On Wed, Jan 6, 2021 at 5:06 PM Pradeep Kumar Nalla <pnalla at marvell.com> wrote:
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: Ferruh Yigit <ferruh.yigit at intel.com>
> >> Sent: Tuesday, January 5, 2021 8:59 PM
> >> To: Pradeep Kumar Nalla <pnalla at marvell.com>
> >> Cc: Jerin Jacob Kollanukkaran <jerinj at marvell.com>; Satananda Burla <sburla at marvell.com>; dev at dpdk.org
> >> Subject: Re: [EXT] Re: [dpdk-dev] [PATCH 00/15] Octeon Tx/Tx2 Endpoint pmd
> >>
> >> On 1/5/2021 2:43 PM, Pradeep Kumar Nalla wrote:
> >>
> >> Please do not top post, reply moved below.
> >>
> >>> Thanks
> >>> Pradeep.
> >>> -----Original Message-----
> >>> From: Ferruh Yigit <ferruh.yigit at intel.com>
> >>> Sent: Monday, January 4, 2021 5:22 PM
> >>> To: Pradeep Kumar Nalla <pnalla at marvell.com>
> >>> Cc: Jerin Jacob Kollanukkaran <jerinj at marvell.com>; Satananda Burla
> >>> <sburla at marvell.com>; dev at dpdk.org
> >>> Subject: [EXT] Re: [dpdk-dev] [PATCH 00/15] Octeon Tx/Tx2 Endpoint pmd
> >>>
> >>> External Email
> >>>
> >>> ----------------------------------------------------------------------
> >>> On 12/31/2020 7:22 AM, Nalla, Pradeep wrote:
> >>>> From: "Nalla Pradeep" <pnalla at marvell.com>
> >>>>
> >>>> This patch set contains PMD with minimal set of operations that can
> >>>> drive both Octeon Tx and Tx2 in endpoint.
> >>>>
> >>>
> >>> Hi Pradeep,
> >>>
> >>> There is already octeontx and octeontx2 net drivers, what is the difference of the 'endpoint' driver, why it is needed, can you please give more information?
> >>>
> >>> Hi Ferruh
> >>>
> >>> This PMD, while running on a host, drives octeontx/octeontx2 over pci bus, where as "OcteonTx and OcteonTx2 net drivers" run on respective Tx/Tx2 SOCs to make use of h/w blocks present on the SOC.
> >>>
> >>> But aren't they same HW block, either in the SoC or external ethernet controller via PCI bus?
> >> No, this pmd doesn't access any h/w block on the soc. When in ep mode octeontx and octeontx2 present themselves as network devices and this pmd will program that interface and does packet rx/tx.
> >>> As far as I can see octeontx2 access the device via PCI bus, why updating the existing driver and adding new device IDs is not working?
> >> OxteonTx2 access H/W blocks on soc which also appear as PCI devices.
> >
> > In other words,
> > - The net/octeontx2 driver has a separate set of HW devices that are
> > not accessible from x86 host.
>
> So is the net/octeontx2 superset of the endpoint driver?
>
> > - Even though net/octeontx2 is based on PCI bus, scope of that PCI bus
> > is internal to SoC. It is an internal bus emulated as PCI to help
> > standard device probing works.
> >
>
> This shouldn't differ from driver perspective, right, for driver it is
> configuring device on PCI bus.
>
> Just to be able to eliminate any code that can be eliminated, what prevents
> using 'net/octeontx2'?
> Like I assume one of the HW block not accessible for EP device is eventdev
> block, is this making required driver change too big, or is it completely
> something else?


No one of the HW devices that is managed by net/octeontx2 is available
to PCI RC HOST.

The architecture is like below: It is for smart NIC kind of use case where
1) octeontx2 is in PCIe form factor(connected to x86)
2) net/octeontx2 driver runs on arm64
3) There will be a DPDK application that's using  net/octeontx2 on
ARM64 and it includes a message server(we call it FW)
4) New PMD(net/octeontx_ep) run on x86, send messages over PCI interface.
5) FW Receives the msg and DPDK app(FW) on ARM64 process it using net/octeonxt2.
These messages are very high level abstracted.
6) FW Transmites back message to x86
7) Step 5 and 6 is the ethdev dev ops for net/octeontx_ep


> Btw, I can see some end point device PCI IDs are already used,
> PCI_DEVID_OCTEONTX2_EP_VF, but it is used by a rawdev driver (raw/octeontx2_ep),
> not sure what it is.

Good point. underlaying HW for raw dev and net/octeontx_ep is the
same. Just that new PMD has a handle for
custom message(with help FW in arm64) to act as ethdev device. We will
see what is the best
method to resolve PCI ID conflit.