Re: [PATCH Xilinx Alveo 1/8] Documentation: fpga: Add a document describing Alveo XRT drivers

Moritz Fischer
2020-12-02T23:11:06Z

Hi Max,

On Wed, Dec 02, 2020 at 09:24:29PM +0000, Max Zhen wrote:
> Hi Moritz,
>
> Thanks for your feedback. Please see my reply inline.
>
> Thanks,
> -Max
>
> > -----Original Message-----
> > From: Moritz Fischer <mdf@kernel.org>
> > Sent: Monday, November 30, 2020 20:55
> > To: Sonal Santan <sonals@xilinx.com>
> > Cc: linux-kernel@vger.kernel.org; linux-fpga@vger.kernel.org; Max Zhen
> > <maxz@xilinx.com>; Lizhi Hou <lizhih@xilinx.com>; Michal Simek
> > <michals@xilinx.com>; Stefano Stabellini <stefanos@xilinx.com>;
> > devicetree@vger.kernel.org
> > Subject: Re: [PATCH Xilinx Alveo 1/8] Documentation: fpga: Add a document
> > describing Alveo XRT drivers
> >
> >
> > On Sat, Nov 28, 2020 at 04:00:33PM -0800, Sonal Santan wrote:
> > > From: Sonal Santan <sonal.santan@xilinx.com>
> > >
> > > Describe Alveo XRT driver architecture and provide basic overview of
> > > Xilinx Alveo platform.
> > >
> > > Signed-off-by: Sonal Santan <sonal.santan@xilinx.com>
> > > ---
> > > Documentation/fpga/index.rst | 1 +
> > > Documentation/fpga/xrt.rst | 588
> > +++++++++++++++++++++++++++++++++++
> > > 2 files changed, 589 insertions(+)
> > > create mode 100644 Documentation/fpga/xrt.rst
> > >
> > > diff --git a/Documentation/fpga/index.rst
> > > b/Documentation/fpga/index.rst index f80f95667ca2..30134357b70d
> > 100644
> > > --- a/Documentation/fpga/index.rst
> > > +++ b/Documentation/fpga/index.rst
> > > @@ -8,6 +8,7 @@ fpga
> > > :maxdepth: 1
> > >
> > > dfl
> > > + xrt
> > >
> > > .. only:: subproject and html
> > >
> > > diff --git a/Documentation/fpga/xrt.rst b/Documentation/fpga/xrt.rst
> > > new file mode 100644 index 000000000000..9f37d46459b0
> > > --- /dev/null
> > > +++ b/Documentation/fpga/xrt.rst
> > > @@ -0,1 +1,588 @@
> > > +==================================
> > > +XRTV2 Linux Kernel Driver Overview
> > > +==================================
> > > +
> > > +XRTV2 drivers are second generation `XRT
> > > +<https://github.com/Xilinx/XRT>`_ drivers which support `Alveo
> > > +<https://www.xilinx.com/products/boards-and-kits/alveo.html>`_ PCIe
> > platforms from Xilinx.
> > > +
> > > +XRTV2 drivers support *subsystem* style data driven platforms where
> > > +driver's configuration and behavior is determined by meta data provided
> > by platform (in *device tree* format).
> > > +Primary management physical function (MPF) driver is called
> > > +**xmgmt**. Primary user physical function (UPF) driver is called
> > > +**xuser** and HW subsystem drivers are packaged into a library module
> > called **xrt-lib**, which is shared by **xmgmt** and **xuser** (WIP).
> > WIP?
>
> Working in progress. I'll expand it in the doc.
>
> > > +
> > > +Alveo Platform Overview
> > > +=======================
> > > +
> > > +Alveo platforms are architected as two physical FPGA partitions:
> > > +*Shell* and *User*. Shell
> > Nit: The Shell provides ...
>
> Sure. Will fix.
>
> > > +provides basic infrastructure for the Alveo platform like PCIe
> > > +connectivity, board management, Dynamic Function Exchange (DFX),
> > > +sensors, clocking, reset, and security. User partition contains user
> > compiled binary which is loaded by a process called DFX also known as partial
> > reconfiguration.
> > > +
> > > +Physical partitions require strict HW compatibility with each other for DFX
> > to work properly.
> > > +Every physical partition has two interface UUIDs: *parent* UUID and
> > > +*child* UUID. For simple single stage platforms Shell → User forms
> > > +parent child relationship. For complex two stage platforms Base → Shell
> > → User forms the parent child relationship chain.
> > > +
> > > +.. note::
> > > + Partition compatibility matching is key design component of Alveo
> > platforms and XRT. Partitions
> > > + have child and parent relationship. A loaded partition exposes child
> > partition UUID to advertise
> > > + its compatibility requirement for child partition. When loading a child
> > partition the xmgmt
> > > + management driver matches parent UUID of the child partition against
> > child UUID exported by the
> > > + parent. Parent and child partition UUIDs are stored in the *xclbin* (for
> > user) or *xsabin* (for
> > > + base and shell). Except for root UUID, VSEC, hardware itself does not
> > know about UUIDs. UUIDs are
> > > + stored in xsabin and xclbin.
> > > +
> > > +
> > > +The physical partitions and their loading is illustrated below::
> > > +
> > > + SHELL USER
> > > + +-----------+ +-------------------+
> > > + | | | |
> > > + | VSEC UUID | CHILD PARENT | LOGIC UUID |
> > > + | o------->|<--------o |
> > > + | | UUID UUID | |
> > > + +-----+-----+ +--------+----------+
> > > + | |
> > > + . .
> > > + | |
> > > + +---+---+ +------+--------+
> > > + | POR | | USER COMPILED |
> > > + | FLASH | | XCLBIN |
> > > + +-------+ +---------------+
> > > +
> > > +
> > > +Loading Sequence
> > > +----------------
> > > +
> > > +Shell partition is loaded from flash at system boot time. It
> > > +establishes the PCIe link and exposes
> > Nit: The Shell
>
> Will fix.
>
> > > +two physical functions to the BIOS. After OS boot, xmgmt driver
> > > +attaches to PCIe physical function
> > > +0 exposed by the Shell and then looks for VSEC in PCIe extended
> > > +configuration space. Using VSEC it determines the logic UUID of Shell
> > > +and uses the UUID to load matching *xsabin* file from Linux firmware
> > > +directory. The xsabin file contains metadata to discover peripherals that
> > are part of Shell and firmware(s) for any embedded soft processors in Shell.
> >
> > Neat.
>
> Thanks :-).
>
> > > +
> > > +Shell exports child interface UUID which is used for compatibility
> > > +check when loading user compiled
> > Nit: The Shell
>
> Sure.
>
> > > +xclbin over the User partition as part of DFX. When a user requests
> > > +loading of a specific xclbin the xmgmt management driver reads the
> > > +parent interface UUID specified in the xclbin and matches it with
> > > +child interface UUID exported by Shell to determine if xclbin is compatible
> > with the Shell. If match fails loading of xclbin is denied.
> > > +
> > > +xclbin loading is requested using ICAP_DOWNLOAD_AXLF ioctl command.
> > > +When loading xclbin xmgmt driver performs the following operations:
> > > +
> > > +1. Sanity check the xclbin contents
> > > +2. Isolate the User partition
> > > +3. Download the bitstream using the FPGA config engine (ICAP) 4.
> > > +De-isolate the User partition
> > Is this modelled as bridges and regions?
>
> Alveo drivers as written today do not use fpga bridge and region framework. It seems that if we add support for that framework, it’s possible to receive PR program request from kernel outside of xmgmt driver? Currently, we can’t support this and PR program can only be initiated using XRT’s runtime API in user space.

I'm not 100% sure I understand the concern here, let me reply to what I
think I understand:

You're worried that if you use FPGA region as interface to accept PR
requests something else could attempt to reconfigure the region from
within the kernel using the FPGA Region API?

Assuming I got this right, I don't think this is a big deal. When you
create the regions you control who gets the references to it.

From what I've seen so far Regions seem to be roughly equivalent to
Partitions, hence my surprise to see a new structure bypassing them.
>
> Or maybe we have missed some points about the use case for this framework?
>
> >
> > > +5. Program the clocks (ClockWiz) driving the User partition 6. Wait
> > > +for memory controller (MIG) calibration
> > > +
> > > +`Platform Loading Overview
> > > +<https://xilinx.github.io/XRT/master/html/platforms_partitions.html>`
> > > +_ provides more detailed information on platform loading.
> > > +
> > > +xsabin
> > > +------
> > > +
> > > +Each Alveo platform comes packaged with its own xsabin. The xsabin is
> > > +trusted component of the platform. For format details refer to
> > > +:ref:`xsabin/xclbin Container Format`. xsabin contains basic
> > > +information like UUIDs, platform name and metadata in the form of
> > device tree. See :ref:`Device Tree Usage` for details and example.
> > > +
> > > +xclbin
> > > +------
> > > +
> > > +xclbin is compiled by end user using
> > > +`Vitis
> > > +<https://www.xilinx.com/products/design-tools/vitis/vitis-platform.ht
> > > +ml>`_ tool set from Xilinx. The xclbin contains sections describing
> > > +user compiled acceleration engines/kernels, memory subsystems,
> > clocking information etc. It also contains bitstream for the user partition,
> > UUIDs, platform name, etc. xclbin uses the same container format as xsabin
> > which is described below.
> > > +
> > > +
> > > +xsabin/xclbin Container Format
> > > +------------------------------
> > > +
> > > +xclbin/xsabin is ELF-like binary container format. It is structured as series
> > of sections.
> > > +There is a file header followed by several section headers which is
> > followed by sections.
> > > +A section header points to an actual section. There is an optional signature
> > at the end.
> > > +The format is defined by header file ``xclbin.h``. The following
> > > +figure illustrates a typical xclbin::
> > > +
> > > +
> > > + +---------------------+
> > > + | |
> > > + | HEADER |
> > > + +---------------------+
> > > + | SECTION HEADER |
> > > + | |
> > > + +---------------------+
> > > + | ... |
> > > + | |
> > > + +---------------------+
> > > + | SECTION HEADER |
> > > + | |
> > > + +---------------------+
> > > + | SECTION |
> > > + | |
> > > + +---------------------+
> > > + | ... |
> > > + | |
> > > + +---------------------+
> > > + | SECTION |
> > > + | |
> > > + +---------------------+
> > > + | SIGNATURE |
> > > + | (OPTIONAL) |
> > > + +---------------------+
> > > +
> > > +
> > > +xclbin/xsabin files can be packaged, un-packaged and inspected using
> > > +XRT utility called **xclbinutil**. xclbinutil is part of XRT open
> > > +source software stack. The source code for xclbinutil can be found at
> > > +https://github.com/Xilinx/XRT/tree/master/src/runtime_src/tools/xclbi
> > > +nutil
> > > +
> > > +For example to enumerate the contents of a xclbin/xsabin use the
> > > +*--info* switch as shown
> > > +below::
> > > +
> > > + xclbinutil --info --input
> > > + /opt/xilinx/firmware/u50/gen3x16-xdma/blp/test/bandwidth.xclbin
> > > + xclbinutil --info --input
> > > + /lib/firmware/xilinx/862c7020a250293e32036f19956669e5/partition.xsab
> > > + in
> > > +
> > > +
> > > +Device Tree Usage
> > > +-----------------
> > > +
> > > +As mentioned previously xsabin stores metadata which advertise HW
> > subsystems present in a partition.
> > > +The metadata is stored in device tree format with well defined
> > > +schema. Subsystem instantiations are captured as children of
> > > +``addressable_endpoints`` node. Subsystem nodes have standard
> > attributes like ``reg``, ``interrupts`` etc. Additionally the nodes also have PCIe
> > specific attributes:
> > > +``pcie_physical_function`` and ``pcie_bar_mapping``. These identify
> > > +which PCIe physical function and which BAR space in that physical
> > > +function the subsystem resides. XRT management driver uses this
> > > +information to bind *platform drivers* to the subsystem
> > > +instantiations. The platform drivers are found in **xrt-lib.ko**
> > > +kernel module defined later. Below is an example of device tree for
> > > +Alveo U50
> > > +platform::
> >
> > I might be missing something, but couldn't you structure the addressable
> > endpoints in a way that encode the physical function as a parent / child
> > relation?
>
> Alveo driver does not generate the metadata. The metadata is formatted and generated by HW tools when the Alveo HW platform is built.

Sure, but you control the tools that generate the metadata :) Your
userland can structure / process it however it wants / needs?
>
> >
> > What are the regs relative to?
>
> Regs indicates offset of the register on the PCIE BAR of the Alveo device.
>
> > > +
> > > + /dts-v1/;
> > > +
> > > + /{
> > > + logic_uuid = "f465b0a3ae8c64f619bc150384ace69b";
> > > +
> > > + schema_version {
> > > + major = <0x01>;
> > > + minor = <0x00>;
> > > + };
> > > +
> > > + interfaces {
> > > +
> > > + @0 {
> > > + interface_uuid = "862c7020a250293e32036f19956669e5";
> > > + };
> > > + };
> > > +
> > > + addressable_endpoints {
> > > +
> > > + ep_blp_rom_00 {
> > > + reg = <0x00 0x1f04000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_bram_ctrl-
> > 1.0\0axi_bram_ctrl";
> > > + };
> > > +
> > > + ep_card_flash_program_00 {
> > > + reg = <0x00 0x1f06000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_quad_spi-
> > 1.0\0axi_quad_spi";
> > > + interrupts = <0x03 0x03>;
> > > + };
> > > +
> > > + ep_cmc_firmware_mem_00 {
> > > + reg = <0x00 0x1e20000 0x00 0x20000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible =
> > > + "xilinx.com,reg_abs-axi_bram_ctrl-1.0\0axi_bram_ctrl";
> > > +
> > > + firmware {
> > > + firmware_product_name = "cmc";
> > > + firmware_branch_name = "u50";
> > > + firmware_version_major = <0x01>;
> > > + firmware_version_minor = <0x00>;
> > > + };
> > > + };
> > > +
> > > + ep_cmc_intc_00 {
> > > + reg = <0x00 0x1e03000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_intc-1.0\0axi_intc";
> > > + interrupts = <0x04 0x04>;
> > > + };
> > > +
> > > + ep_cmc_mutex_00 {
> > > + reg = <0x00 0x1e02000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_cmc_regmap_00 {
> > > + reg = <0x00 0x1e08000 0x00 0x2000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible =
> > > + "xilinx.com,reg_abs-axi_bram_ctrl-1.0\0axi_bram_ctrl";
> > > +
> > > + firmware {
> > > + firmware_product_name = "sc-fw";
> > > + firmware_branch_name = "u50";
> > > + firmware_version_major = <0x05>;
> > > + };
> > > + };
> > > +
> > > + ep_cmc_reset_00 {
> > > + reg = <0x00 0x1e01000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_ddr_mem_calib_00 {
> > > + reg = <0x00 0x63000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_debug_bscan_mgmt_00 {
> > > + reg = <0x00 0x1e90000 0x00 0x10000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-debug_bridge-
> > 1.0\0debug_bridge";
> > > + };
> > > +
> > > + ep_ert_base_address_00 {
> > > + reg = <0x00 0x21000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_ert_command_queue_mgmt_00 {
> > > + reg = <0x00 0x40000 0x00 0x10000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-ert_command_queue-
> > 1.0\0ert_command_queue";
> > > + };
> > > +
> > > + ep_ert_command_queue_user_00 {
> > > + reg = <0x00 0x40000 0x00 0x10000>;
> > > + pcie_physical_function = <0x01>;
> > > + compatible = "xilinx.com,reg_abs-ert_command_queue-
> > 1.0\0ert_command_queue";
> > > + };
> > > +
> > > + ep_ert_firmware_mem_00 {
> > > + reg = <0x00 0x30000 0x00 0x8000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible =
> > > + "xilinx.com,reg_abs-axi_bram_ctrl-1.0\0axi_bram_ctrl";
> > > +
> > > + firmware {
> > > + firmware_product_name = "ert";
> > > + firmware_branch_name = "v20";
> > > + firmware_version_major = <0x01>;
> > > + };
> > > + };
> > > +
> > > + ep_ert_intc_00 {
> > > + reg = <0x00 0x23000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_intc-1.0\0axi_intc";
> > > + interrupts = <0x05 0x05>;
> > > + };
> > > +
> > > + ep_ert_reset_00 {
> > > + reg = <0x00 0x22000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_ert_sched_00 {
> > > + reg = <0x00 0x50000 0x00 0x1000>;
> > > + pcie_physical_function = <0x01>;
> > > + compatible = "xilinx.com,reg_abs-ert_sched-1.0\0ert_sched";
> > > + interrupts = <0x09 0x0c>;
> > > + };
> > > +
> > > + ep_fpga_configuration_00 {
> > > + reg = <0x00 0x1e88000 0x00 0x8000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_hwicap-1.0\0axi_hwicap";
> > > + interrupts = <0x02 0x02>;
> > > + };
> > > +
> > > + ep_icap_reset_00 {
> > > + reg = <0x00 0x1f07000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_mailbox_mgmt_00 {
> > > + reg = <0x00 0x1f10000 0x00 0x10000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-mailbox-1.0\0mailbox";
> > > + interrupts = <0x00 0x00>;
> > > + };
> > > +
> > > + ep_mailbox_user_00 {
> > > + reg = <0x00 0x1f00000 0x00 0x10000>;
> > > + pcie_physical_function = <0x01>;
> > > + compatible = "xilinx.com,reg_abs-mailbox-1.0\0mailbox";
> > > + interrupts = <0x08 0x08>;
> > > + };
> > > +
> > > + ep_msix_00 {
> > > + reg = <0x00 0x00 0x00 0x20000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-msix-1.0\0msix";
> > > + pcie_bar_mapping = <0x02>;
> > > + };
> > > +
> > > + ep_pcie_link_mon_00 {
> > > + reg = <0x00 0x1f05000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_pr_isolate_plp_00 {
> > > + reg = <0x00 0x1f01000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_pr_isolate_ulp_00 {
> > > + reg = <0x00 0x1000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_uuid_rom_00 {
> > > + reg = <0x00 0x64000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_bram_ctrl-
> > 1.0\0axi_bram_ctrl";
> > > + };
> > > +
> > > + ep_xdma_00 {
> > > + reg = <0x00 0x00 0x00 0x10000>;
> > > + pcie_physical_function = <0x01>;
> > > + compatible = "xilinx.com,reg_abs-xdma-1.0\0xdma";
> > > + pcie_bar_mapping = <0x02>;
> > > + };
> > > + };
> > > +
> > > + }
> > > +
> > > +
> > > +
> > > +Deployment Models
> > > +=================
> > > +
> > > +Baremetal
> > > +---------
> > > +
> > > +In bare-metal deployments both MPF and UPF are visible and
> > > +accessible. xmgmt driver binds to MPF. xmgmt driver operations are
> > > +privileged and available to system administrator. The full stack is
> > illustrated below::
> > > +
> > > +
> > > + HOST
> > > +
> > > + [XMGMT] [XUSER]
> > > + | |
> > > + | |
> > > + +-----+ +-----+
> > > + | MPF | | UPF |
> > > + | | | |
> > > + | PF0 | | PF1 |
> > > + +--+--+ +--+--+
> > > + ......... ^................. ^..........
> > > + | |
> > > + | PCIe DEVICE |
> > > + | |
> > > + +--+------------------+--+
> > > + | SHELL |
> > > + | |
> > > + +------------------------+
> > > + | USER |
> > > + | |
> > > + | |
> > > + | |
> > > + | |
> > > + +------------------------+
> > > +
> > > +
> > > +
> > > +Virtualized
> > > +-----------
> > > +
> > > +In virtualized deployments privileged MPF is assigned to host but
> > > +unprivileged UPF is assigned to guest VM via PCIe pass-through. xmgmt
> > driver in host binds to MPF.
> > > +xmgmt driver operations are privileged and only accessible by hosting
> > service provider.
> > > +The full stack is illustrated below::
> > > +
> > > +
> > > + .............
> > > + HOST . VM .
> > > + . .
> > > + [XMGMT] . [XUSER] .
> > > + | . | .
> > > + | . | .
> > > + +-----+ . +-----+ .
> > > + | MPF | . | UPF | .
> > > + | | . | | .
> > > + | PF0 | . | PF1 | .
> > > + +--+--+ . +--+--+ .
> > > + ......... ^................. ^..........
> > > + | |
> > > + | PCIe DEVICE |
> > > + | |
> > > + +--+------------------+--+
> > > + | SHELL |
> > > + | |
> > > + +------------------------+
> > > + | USER |
> > > + | |
> > > + | |
> > > + | |
> > > + | |
> > > + +------------------------+
> > > +
> > > +
> > > +
> > > +Driver Modules
> > > +==============
> > > +
> > > +xrt-lib.ko
> > > +----------
> > > +
> > > +Repository of all subsystem drivers and pure software modules that
> > > +can potentially be shared between xmgmt and xuser. All these drivers
> > > +are structured as Linux *platform driver* and are instantiated by
> > > +xmgmt (or xuser in future) based on meta data associated with
> > > +hardware. The metadata is in the form of device tree as explained before.
> > > +
> > > +xmgmt.ko
> > > +--------
> > > +
> > > +The xmgmt driver is a PCIe device driver driving MPF found on
> > > +Xilinx's Alveo PCIE device. It consists of one *root* driver, one or
> > > +more *partition* drivers and one or more *leaf* drivers. The root and
> > > +MPF specific leaf drivers are in xmgmt.ko. The partition driver and other
> > leaf drivers are in xrt-lib.ko.
> > > +
> > > +The instantiation of specific partition driver or leaf driver is
> > > +completely data driven based on meta data (mostly in device tree
> > > +format) found through VSEC capability and inside firmware files, such
> > > +as xsabin or xclbin file. The root driver manages life cycle of
> > > +multiple partition drivers, which, in turn, manages multiple leaf
> > > +drivers. This allows a single set of driver code to support all kinds
> > > +of subsystems exposed by different shells. The difference among all
> > > +these subsystems will be handled in leaf drivers with root and
> > > +partition drivers being part of the infrastructure and provide common
> > services for all leaves found on all platforms.
> > > +
> > > +
> > > +xmgmt-root
> > > +^^^^^^^^^^
> > > +
> > > +The xmgmt-root driver is a PCIe device driver attaches to MPF. It's
> > > +part of the
> > Nit: s/attaches/attached ?
>
> Yes, sure.
>
> > > +infrastructure of the MPF driver and resides in xmgmt.ko. This driver
> > > +
> > > +* manages one or more partition drivers
> > > +* provides access to functionalities that requires pci_dev, such as
> > > +PCIE config
> > > + space access, to other leaf drivers through parent calls
> > > +* together with partition driver, facilities event callbacks for
> > > +other leaf drivers
> > > +* together with partition driver, facilities inter-leaf driver calls
> > > +for other leaf
> > > + drivers
> > > +
> > > +When root driver starts, it will explicitly create an initial
> > > +partition instance, which contains leaf drivers that will trigger the
> > > +creation of other partition instances. The root driver will wait for
> > > +all partitions and leaves to be created before it returns from it's
> > > +probe routine and claim success of the initialization of the entire xmgmt
> > driver.
> > > +
> > > +partition
> > > +^^^^^^^^^
> > > +
> > > +The partition driver is a platform device driver whose life cycle is
> > > +managed by root and does not have real IO mem or IRQ resources. It's
> > > +part of the infrastructure of the MPF driver and resides in
> > > +xrt-lib.ko. This driver
> > > +
> > > +* manages one or more leaf drivers so that multiple leaves can be
> > > +managed as a group
> > > +* provides access to root from leaves, so that parent calls, event
> > > +notifications
> > > + and inter-leaf calls can happen
> > > +
> > > +In xmgmt, an initial partition driver instance will be created by
> > > +root, which contains leaves that will trigger partition instances to
> > > +be created to manage groups of leaves found on different partitions
> > > +on hardware, such as VSEC, Shell, and User.
> > > +
> > > +leaves
> > > +^^^^^^
> > > +
> > > +The leaf driver is a platform device driver whose life cycle is
> > > +managed by a partition driver and may or may not have real IO mem or
> > > +IRQ resources. They are the real meat of xmgmt and contains platform
> > > +specific code to Shell and User found on a MPF.
> > > +
> > > +A leaf driver may not have real hardware resources when it merely
> > > +acts as a driver that manages certain in-memory states for xmgmt.
> > > +These in-memory states could be shared by multiple other leaves.
> > > +
> > > +Leaf drivers assigned to specific hardware resources drive specific
> > > +subsystem in the device. To manipulate the subsystem or carry out a
> > > +task, a leaf driver may ask help from root via parent calls and/or from
> > other leaves via inter-leaf calls.
> > > +
> > > +A leaf can also broadcast events through infrastructure code for
> > > +other leaves to process. It can also receive event notification from
> > > +infrastructure about certain events, such as post-creation or pre-exit of a
> > particular leaf.
> > > +
> > > +
> > > +Driver Interfaces
> > > +=================
> > > +
> > > +xmgmt Driver Ioctls
> > > +-------------------
> > > +
> > > +Ioctls exposed by xmgmt driver to user space are enumerated in the
> > following table:
> > > +
> > > +== ===================== =============================
> > ===========================
> > > +# Functionality ioctl request code data format
> > > +== ===================== =============================
> > ===========================
> > > +1 FPGA image download XMGMT_IOCICAPDOWNLOAD_AXLF
> > xmgmt_ioc_bitstream_axlf
> > > +2 CL frequency scaling XMGMT_IOCFREQSCALE
> > xmgmt_ioc_freqscaling
> > > +== ===================== =============================
> > > +===========================
> > > +
> > > +xmgmt Driver Sysfs
> > > +------------------
> > > +
> > > +xmgmt driver exposes a rich set of sysfs interfaces. Subsystem
> > > +platform drivers export sysfs node for every platform instance.
> > > +
> > > +Every partition also exports its UUIDs. See below for examples::
> > > +
> > > + /sys/bus/pci/devices/0000:06:00.0/xmgmt_main.0/interface_uuids
> > > + /sys/bus/pci/devices/0000:06:00.0/xmgmt_main.0/logic_uuids
> > > +
> > > +
> > > +hwmon
> > > +-----
> > > +
> > > +xmgmt driver exposes standard hwmon interface to report voltage,
> > > +current, temperature, power, etc. These can easily be viewed using
> > *sensors* command line utility.
> > > +
> > > +
> > > +mailbox
> > > +-------
> > > +
> > > +xmgmt communicates with user physical function driver via HW mailbox.
> > > +Mailbox opcodes are defined in ``mailbox_proto.h``. `Mailbox
> > > +Inter-domain Communication Protocol
> > > +<https://xilinx.github.io/XRT/master/html/mailbox.proto.html>`_
> > > +defines the full specification. xmgmt implements subset of the
> > specification. It provides the following services to the UPF driver:
> > > +
> > > +1. Responding to *are you there* request including determining if the
> > two drivers are
> > > + running in the same OS domain
> > > +2. Provide sensor readings, loaded xclbin UUID, clock frequency, shell
> > information, etc.
> > > +3. Perform PCIe hot reset
> > > +4. Download user compiled xclbin
> >
> > Is this gonna use the mailbox framework?
>
> The xclbin can be downloaded via IOCTL interface of xmgmt driver.
> Or the download request can come from user pf driver via mailbox, yes.
>
> Thanks,
> Max
>
> >
> > > +
> > > +
> > > +Platform Security Considerations
> > > +================================
> > > +
> > > +`Security of Alveo Platform
> > > +<https://xilinx.github.io/XRT/master/html/security.html>`_
> > > +discusses the deployment options and security implications in great detail.
> > > --
> > > 2.17.1
> >
> > That's a lot of text, I'll have to read it again most likely,
> >
> > - Moritz

Thanks,
Moritz