[v1,1/1] docs/system/arm: Document the Xilinx Versal Virt board

diff --git a/docs/system/arm/xlnx-versal-virt.rst b/docs/system/arm/xlnx-versal-virt.rst
new file mode 100644
index 0000000000..2602d0f995
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+++ b/docs/system/arm/xlnx-versal-virt.rst
@@ -0,0 +1,176 @@ 
+Xilinx Versal Virt (``xlnx-versal-virt``)
+=========================================
+
+Xilinx Versal is a family of heterogeneous multi-core SoCs
+(System on Chip) that combine traditional hardened CPUs and I/O
+peripherals in a Processing System (PS) with runtime programmable
+FPGA logic (PL) and an Artificial Intelligence Engine (AIE).
+
+More details here:
+https://www.xilinx.com/products/silicon-devices/acap/versal.html
+
+The family of Versal SoCs share a single architecture but come in
+different parts with different speed grades, amounts of PL and
+other differences.
+
+The Xilinx Versal Virt board in QEMU is a model of a virtual board
+(does not exist in reality) with a virtual Versal SoC without I/O
+limitations. Currently, we support the following cores and devices:
+
+Implemented CPU cores:
+
+- 2 ACPUs (ARM Cortex-A72)
+
+Implemented devices:
+
+- Interrupt controller (ARM GICv3)
+- 2 UARTs (ARM PL011)
+- An RTC (Versal built-in)
+- 2 GEMs (Cadence MACB Ethernet MACs)
+- 8 ADMA (Xilinx zDMA) channels
+- 2 SD Controllers
+- OCM (256KB of On Chip Memory)
+- DDR memory
+
+QEMU does not yet model any other devices, including the PL and the AI Engine.
+
+Other differences between the hardware and the QEMU model:
+
+- QEMU allows the amount of DDR memory provided to be specified with the
+  ``-m`` argument. If a DTB is provided on the command line then QEMU will
+  edit it to include suitable entries describing the Versal DDR memory ranges.
+
+- QEMU provides 8 virtio-mmio virtio transports; these start at
+  address ``0xa0000000`` and have IRQs from 111 and upwards.
+
+Running
+"""""""
+If the user provides an Operating System to be loaded, we expect users
+to use the ``-kernel`` command line option.
+
+Users can load firmware or boot-loaders with the ``-device loader`` options.
+
+When loading an OS, QEMU generates a DTB and selects an appropriate address
+where it gets loaded. This DTB will be passed to the kernel in register x0.
+
+If there's no ``-kernel`` option, we generate a DTB and place it at 0x1000
+for boot-loaders or firmware to pick it up.
+
+If users want to provide their own DTB, they can use the ``-dtb`` option.
+These DTBs will have their memory nodes modified to match QEMU's
+selected ram_size option before they get passed to the kernel or FW.
+
+When loading an OS, we turn on QEMU's PSCI implementation with SMC
+as the PSCI conduit. When there's no ``-kernel`` option, we assume the user
+provides EL3 firmware to handle PSCI.
+
+A few examples:
+
+Direct Linux boot of a generic ARM64 upstream Linux kernel:
+
+.. code-block:: bash
+
+  $ qemu-system-aarch64 -M xlnx-versal-virt -m 2G \
+      -serial mon:stdio -display none \
+      -kernel arch/arm64/boot/Image \
+      -nic user -nic user \
+      -device virtio-rng-device,bus=virtio-mmio-bus.0 \
+      -drive if=none,index=0,file=hd0.qcow2,id=hd0,snapshot \
+      -drive file=qemu_sd.qcow2,if=sd,index=0,snapshot \
+      -device virtio-blk-device,drive=hd0 -append root=/dev/vda
+
+Direct Linux boot of PetaLinux 2019.2:
+
+.. code-block:: bash
+
+  $ qemu-system-aarch64  -M xlnx-versal-virt -m 2G \
+      -serial mon:stdio -display none \
+      -kernel petalinux-v2019.2/Image \
+      -append "rdinit=/sbin/init console=ttyAMA0,115200n8 earlycon=pl011,mmio,0xFF000000,115200n8" \
+      -net nic,model=cadence_gem,netdev=net0 -netdev user,id=net0 \
+      -device virtio-rng-device,bus=virtio-mmio-bus.0,rng=rng0 \
+      -object rng-random,filename=/dev/urandom,id=rng0
+
+Boot PetaLinux 2019.2 via ARM Trusted Firmware (2018.3 because the 2019.2
+version of ATF tries to configure the CCI which we don't model) and U-boot:
+
+.. code-block:: bash
+
+  $ qemu-system-aarch64 -M xlnx-versal-virt -m 2G \
+      -serial stdio -display none \
+      -device loader,file=petalinux-v2018.3/bl31.elf,cpu-num=0 \
+      -device loader,file=petalinux-v2019.2/u-boot.elf \
+      -device loader,addr=0x20000000,file=petalinux-v2019.2/Image \
+      -nic user -nic user \
+      -device virtio-rng-device,bus=virtio-mmio-bus.0,rng=rng0 \
+      -object rng-random,filename=/dev/urandom,id=rng0
+
+Run the following at the U-Boot prompt:
+
+.. code-block:: bash
+
+  Versal>
+  fdt addr $fdtcontroladdr
+  fdt move $fdtcontroladdr 0x40000000
+  fdt set /timer clock-frequency <0x3dfd240>
+  setenv bootargs "rdinit=/sbin/init maxcpus=1 console=ttyAMA0,115200n8 earlycon=pl011,mmio,0xFF000000,115200n8"
+  booti 20000000 - 40000000
+  fdt addr $fdtcontroladdr
+
+Boot Linux as DOM0 on Xen via U-Boot:
+
+.. code-block:: bash
+
+  $ qemu-system-aarch64 -M xlnx-versal-virt -m 4G \
+      -serial stdio -display none \
+      -device loader,file=petalinux-v2019.2/u-boot.elf,cpu-num=0 \
+      -device loader,addr=0x30000000,file=linux/2018-04-24/xen \
+      -device loader,addr=0x40000000,file=petalinux-v2019.2/Image \
+      -nic user -nic user \
+      -device virtio-rng-device,bus=virtio-mmio-bus.0,rng=rng0 \
+      -object rng-random,filename=/dev/urandom,id=rng0
+
+Run the following at the U-Boot prompt:
+
+.. code-block:: bash
+
+  Versal>
+  fdt addr $fdtcontroladdr
+  fdt move $fdtcontroladdr 0x20000000
+  fdt set /timer clock-frequency <0x3dfd240>
+  fdt set /chosen xen,xen-bootargs "console=dtuart dtuart=/uart@ff000000 dom0_mem=640M bootscrub=0 maxcpus=1 timer_slop=0"
+  fdt set /chosen xen,dom0-bootargs "rdinit=/sbin/init clk_ignore_unused console=hvc0 maxcpus=1"
+  fdt mknode /chosen dom0
+  fdt set /chosen/dom0 compatible "xen,multiboot-module"
+  fdt set /chosen/dom0 reg <0x00000000 0x40000000 0x0 0x03100000>
+  booti 30000000 - 20000000
+
+Boot Linux as Dom0 on Xen via ARM Trusted Firmware and U-Boot:
+
+.. code-block:: bash
+
+  $ qemu-system-aarch64 -M xlnx-versal-virt -m 4G \
+      -serial stdio -display none \
+      -device loader,file=petalinux-v2018.3/bl31.elf,cpu-num=0 \
+      -device loader,file=petalinux-v2019.2/u-boot.elf \
+      -device loader,addr=0x30000000,file=linux/2018-04-24/xen \
+      -device loader,addr=0x40000000,file=petalinux-v2019.2/Image \
+      -nic user -nic user \
+      -device virtio-rng-device,bus=virtio-mmio-bus.0,rng=rng0 \
+      -object rng-random,filename=/dev/urandom,id=rng0
+
+Run the following at the U-Boot prompt:
+
+.. code-block:: bash
+
+  Versal>
+  fdt addr $fdtcontroladdr
+  fdt move $fdtcontroladdr 0x20000000
+  fdt set /timer clock-frequency <0x3dfd240>
+  fdt set /chosen xen,xen-bootargs "console=dtuart dtuart=/uart@ff000000 dom0_mem=640M bootscrub=0 maxcpus=1 timer_slop=0"
+  fdt set /chosen xen,dom0-bootargs "rdinit=/sbin/init clk_ignore_unused console=hvc0 maxcpus=1"
+  fdt mknode /chosen dom0
+  fdt set /chosen/dom0 compatible "xen,multiboot-module"
+  fdt set /chosen/dom0 reg <0x00000000 0x40000000 0x0 0x03100000>
+  booti 30000000 - 20000000
+
diff --git a/docs/system/target-arm.rst b/docs/system/target-arm.rst
index 4c5b0e4aab..afdb37e738 100644
--- a/docs/system/target-arm.rst
+++ b/docs/system/target-arm.rst
@@ -93,6 +93,7 @@  undocumented; you can get a complete list by running
    arm/sx1
    arm/stellaris
    arm/virt
+   arm/xlnx-versal-virt
 
 Arm CPU features
 ================
diff --git a/MAINTAINERS b/MAINTAINERS
index 0886eb3d2b..5a22c8be42 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -894,7 +894,7 @@  F: hw/misc/zynq*
 F: include/hw/misc/zynq*
 X: hw/ssi/xilinx_*
 
-Xilinx ZynqMP
+Xilinx ZynqMP and Versal
 M: Alistair Francis <alistair@alistair23.me>
 M: Edgar E. Iglesias <edgar.iglesias@gmail.com>
 M: Peter Maydell <peter.maydell@linaro.org>
@@ -905,6 +905,7 @@  F: include/hw/*/xlnx*.h
 F: include/hw/ssi/xilinx_spips.h
 F: hw/display/dpcd.c
 F: include/hw/display/dpcd.h
+F: docs/system/arm/xlnx-versal-virt.rst
 
 ARM ACPI Subsystem
 M: Shannon Zhao <shannon.zhaosl@gmail.com>