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Host PC hw_server Application
The Vivado IDE is used to connect to the
hw_server
application to use the debug feature for
remote or local FPGA targets, including when using HSDP-over-PCIe. The Vivado IDE application
can be running on a remote or local PC and connects to the host PC using a TCP/IP socket, which
is running
hw_server
and connected to the hardware target via PCIe link. The HSDP-over-PCIe
driver acts as a conduit for
hw_server
to serve, receive debug, and trace data to the target
device and display it to the Vivado IDE.
HSDP-over-PCIe Enabled FPGA Design
Traditionally, hardware debug through Vivado is performed over a JTAG interface. For Versal
ACAP, the JTAG datapath to the DPC is hardened and abstracted away using Vivado IDE. Making
debug seamless requires that the connections are established among the debug target(s), DPC,
and debug target clock(s) are active and reset(s) are deasserted. To enable the HSDP-over-PCIe
feature on a Versal ACAP device, there are several design requirements that must be met. As
mentioned previously, there are two distinct methods to exercise the HSDP-over-PCIe feature
such as mgmt mode and user mode. Each of these methods has its own design requirements and
supporting driver code.
User Mode
The user mode method for HSDP-over-PCIe imposes fewer requirements on the hardware
design, but it is also slower than management mode and does not allow for debug access to
hardened blocks like SYSMON, DDRMC, and IBERT. User mode must employ a PCIe BAR to
access a fabric debug hub from the host PC, which bypasses the DPC entirely and does not
operate using DTPs. Instead, the host PC uses memory mapped reads and writes to directly
access the debug hub to issue and collect debug data. User mode is identical on CPM4 and
CPM5 capable devices and it is recommended to use CPM in DMA mode to easily make use of
the AXI Bridge Master type for the PCIe BAR required to reach the debug hub. Debug
transactions are then routed through the NOC to the fabric, which opens the possibility to use
NOC NMU remapping to ensure the PCIe BAR size remains small and the device address map
does not become fragmented.
Appendix D: Using the High Speed Debug Port Over PCIe for Design Debug
PG346 (v3.3) November 16, 2022
CPM Mode for PCI Express
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