> -----Original Message-----
> From: Huang, Wei <wei.hu...@intel.com>
> Sent: Friday, May 27, 2022 4:34 PM
> To: dev@dpdk.org; tho...@monjalon.net; nipun.gu...@nxp.com;
> hemant.agra...@nxp.com
> Cc: sta...@dpdk.org; Xu, Rosen <rosen...@intel.com>; Zhang, Tianfei
> <tianfei.zh...@intel.com>; Zhang, Qi Z <qi.z.zh...@intel.com>; Huang, Wei
> <wei.hu...@intel.com>
> Subject: [PATCH v4 5/5] guides/rawdevs: add description of ofs in ifpga doc
>
> OFS (Open FPGA Stack) specification is introduced briefly.
>
> Signed-off-by: Wei Huang <wei.hu...@intel.com>
> Reviewed-by: Rosen Xu <rosen...@intel.com>
> ---
> v2: update description per Tianfei's comment
> ---
> doc/guides/rawdevs/ifpga.rst | 105
> ++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 104 insertions(+), 1 deletion(-)
>
> diff --git a/doc/guides/rawdevs/ifpga.rst b/doc/guides/rawdevs/ifpga.rst index
> dbd0d6e..3dce57a 100644
> --- a/doc/guides/rawdevs/ifpga.rst
> +++ b/doc/guides/rawdevs/ifpga.rst
> @@ -1,5 +1,5 @@
> .. SPDX-License-Identifier: BSD-3-Clause
> - Copyright(c) 2018 Intel Corporation.
> + Copyright(c) 2018-2022 Intel Corporation.
>
> IFPGA Rawdev Driver
> ======================
> @@ -100,3 +100,106 @@ The following device parameters are supported:
>
> If null, the AFU Bit Stream has been PR in FPGA, if not forces PR and
> identifies AFU Bit Stream file.
> +
> +
> +Open FPGA Stack
> +=====================
> +
> +Open FPGA Stack (OFS) is a collection of RTL and open source software
> +providing interfaces to access the instantiated RTL easily in an FPGA.
> +OFS leverages the DFL for the implementation of the FPGA RTL design.
> +
> +OFS designs allow for the arrangement of software interfaces across
> +multiple PCIe endpoints. Some of these interfaces may be PFs defined in
> +the static region that connect to interfaces in an IP that is loaded via
> Partial
> Reconfiguration (PR).
> +And some of these interfaces may be VFs defined in the PR region that
> +can be reconfigured by the end-user. Furthermore, these PFs/VFs may use
> +DFLs such that features may be discovered and accessed in user space
> +with the aid of a generic kernel driver like vfio-pci. The diagram
> +below depicts an example design with one PF and two VFs. In this
> +example, it will export the management functions via PF0 and
> +acceleration functions via VF0 and VF1, leverage VFIO to export the MMIO
> space to an application.::
> +
> + +-----------------+ +-------------+ +------------+
> + | FPGA Management | | DPDK App | | User App |
> + | App | | | | |
> + +--------+--------+ +------+------+ +-----+------+
> + | | |
> + +--------+--------+ +------+------+ |
> + |IFPGA PMD driver | |AFU MF driver| |
> + +--------+--------+ +------+------+ |
> + | | |
> + +--------+------------------+---------------+------+
> + | VFIO-PCI |
> + +--------+------------------+---------------+------+
> + | | |
> + +--------+--------+ +------+------+ +----+------+
> + | PF0 | | PF0_VF0 | | PF0_VF1 |
> + +-----------------+ +-------------+ +-----------+
> +
> +As accelerators are specialized hardware, they are typically limited in
> +the number installed in a given system. Many use cases require them to
> +be shared across multiple software contexts or threads of software
> +execution, either through partitioning of individual dedicated
> +resources, or virtualization of shared resources. OFS provides several
> +models to share the AFU resources via PR mechanism and hardware-based
> virtualization schemes.
> +
> +1. Legacy model.
> + With legacy model FPGA cards like Intel PAC N3000 or N5000, there is
> + a notion that the boundary between the AFU and the shell is also the unit
> of
> + PR for those FPGA platforms. This model is only able to handle a
> + single context, because it only has one PR engine, and one PR region which
> + has an associated Port device.
> +2. Multiple VFs per PR slot.
> + In this model, available AFU resources may allow instantiation of many VFs
> + which have a dedicated PCIe function with their own dedicated MMIO space,
> or
> + partition a region of MMIO space on a single PCIe function. Intel PAC
> N6000
> + card has implemented this model.
> + In this model, the AFU/PR slot was not connected to port device. For DFL's
> view,
> + the Next_AFU pointer in FIU feature header of port device points to NULL
> in
> this
> + model. On the other hand, each VF can start with an AFU feature header
> without
> + being connected to a FIU Port feature header.
> +
> +The VFs are created through the Linux kernel driver before we use them in
> DPDK.
> +
> +OFS provides the diversity for accessing the AFU resource to RTL developer.
> +An IP designer may choose to add more than one PF for interfacing with
> +IP on the FPGA and choose different model to access the AFU resource.
> +
> +There is one reference architecture design using the "Multiple VFs per PR
> slot"
> +model for OFS as illustrated below. In this reference design, it
> +exports the FPGA management functions via PF0. PF1 will bind with DPDK
> +virtio driver presenting itself as a network interface to the
> +application. PF2 will bind to the vfio-pci driver allowing the user
> +space software to discover and interface with the specific workload
> +like diagnostic test. It leverages AFU PMD driver to access the AFU
> resources in
> DPDK.::
> +
> + +----------------------+
> + | PF/VF mux/demux |
> + +--+--+-----+------+-+-+
> + | | | | |
> + +------------------------+ | | | |
> + PF0 | +---------+ +-+ | |
> + +---+---+ | +---+----+ | |
> + | DFH | | | DFH | | |
> + +-------+ +-----+----+ +--------+ | |
> + | FME | | VirtIO | | Test | | |
> + +---+---+ +----------+ +--------+ | |
> + | PF1 PF2 | |
> + | | |
> + | +----------+ |
> + | | ++
> + | | |
> + | | PF0_VF0 | PF0_VF1
> + | +-----------------+-----------+------------+
> + | | +-----+-----------+--------+ |
> + | | | | | | |
> + | | +------+ | +--+ -+ +--+---+ | |
> + | | | Port | | | DFH | | DFH | | |
> + +-----------+ +------+ | +-----+ +------+ | |
> + | | | DEV | | DEV | | |
> + | | +-----+ +------+ | |
> + | | PR Slot | |
> + | +--------------------------+ |
> + | Port Gasket |
> + +------------------------------------------+
> --
It looks good for me, you can add:
Acked-by: Tianfei Zhang <tianfei.zh...@intel.com>
