The purpose of this page is to describe the build and execution of the FreeRTOS application as a Xen guest on Zynq UltraScale+ MPSoC using PetaLinux and Xilinx xsct Tools.

Source Vitis settings.sh
xsct
set WORKSPACE .
setws -switch $WORKSPACE
app create -name <app name> -template {template app name} -proc psu_cortexa53_0 -hw {xsa path} -os freertos10_xilinx
bsp config stdin psu_uart_1
bsp config stdout psu_uart_1
bsp config hypervisor_guest true
Go to application source path and modify the linker script start address to 0x40000000 as shown below,

Note: Xen guest address space always starts from 0x40000000, so updating linker script to load executable sections starting from 0x40000000.

/* Define Memories in the system */

MEMORY
{
   psu_ddr_0_MEM_0 : ORIGIN = 0x40000000, LENGTH = 0x100000
   psu_ddr_1_MEM_0 : ORIGIN = 0x800000000, LENGTH = 0x80000000
   psu_ocm_ram_0_MEM_0 : ORIGIN = 0xFFFC0000, LENGTH = 0x40000
   psu_qspi_linear_0_MEM_0 : ORIGIN = 0xC0000000, LENGTH = 0x20000000
}

app build -name <application name>
Run command to generate BIN file from executable "aarch64-linux-gnu-objcopy -O binary --gap-fill 0 <elf path> BOOT.BIN"

Configuring Xen

As FreeRTOS uses UART1 for stdout/stdin and TTC0 as tick timer, both of them need to be marked as passthrough in xen-overlay.dtsi. Apart from UART1/TTC0, if application is using any other peripheral device, corresponding nodes also need to be updated with passthrough property.

Example:

UART1 and TTC0 device can be passthrough in xen-overlay.dtsi, as shown below.

&uart1 {
   xen,passthrough = <0x1>;
};

&ttc0 {
   xen,passthrough = <0x1>;
};

Config file for FreeRTOS hello world application would look like as given below.

# =====================================================================
# Example FreeRTOS Guest configuration
# =====================================================================

# Guest name
name = "freertos hello world"

# Kernel image to boot
kernel = "BOOT.BIN"

# Kernel command line options - Allocate 8MB
memory = 8

# Number of VCPUS
vcpus = 1

# Pin to CPU 0
cpus = [1]
irqs = [ 68, 69, 70, 54 ]
iomem = [ "0xff010,1", "0xff110,1" ]

Note- ‘irq' parameter in config file specifies TTC0 (68-70) and UART1 interrupt ID’s , for specific peripheral in Zynq UltraScale+ MPSoC interrupt id can be found in “System Interrupts“ section of TRM

Executing the Application

Procedure is similar to baremetal domU guest as explained in https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842536#XENEL1BaremetalDomU-HowtoExecuteanEL1DomUBaremetalApplication .

Xilinx Wiki

FreeRTOS support for EL1 NS domU guest

Table of Contents

Building the FreeRTOS Application

Configuring Xen

Executing the Application