2.0 KiB
FASM Proof of Concept using Vivado Partial Reconfig flow
top.v is a top-level design that routes a variety of signal into a black-box region of interest (ROI). Vivado's Partial Reconfiguration flow (see UG909 and UG947) is used to implement that design and obtain a bitstream that configures portions of the chip that are currently undocumented.
Designs that fit within the ROI are written in FASM and merged with the above harness into a bitstream with fasm2frame and xc7patch.
Usage
make rules are provided for generating each step of the process so that intermediate forms can be analyzed. Assuming you have a .fasm file, invoking the %.hand_crafted.bit rule will generate a merged bitstream:
make foo.hand\_crafted.bit # reads foo.fasm
Using Vivado to generate .fasm
Vivado's Partial Reconfiguration flow can be used to synthesize and implement a design that is then converted to .fasm. The basic process is to write a module that exactly matches the roi blackbox in the top-level design. Note that even the name of the module must match exactly. Once you have a design, the first step is to synthesize the design with -mode out_of_context:
read_verilog <design>.v
synth_design -mode out_of_context -top roi -part $::env(XRAY_PART)
write_checkpoint -force <design>.dcp
Next, implement that design within the harness. Run 'make harness_routed.dcp' if it doesn't already exist. The following TCL will load the fully-routed harness, load your synthesized design, and generate a bitstream containing both:
open_checkpoint -force harness_routed.dcp
read_checkpoint -cell <design>.dcp
opt_design
place_design
route_design
write_checkpoint -force <design>_routed.dcp
write_bitstream -force <design>_routed.bit
'make _routed.fasm' will run a sequence of tools to extract the bits that are inside the ROI and convert them to FASM. The resulting .fasm can be used to generate a marged bitstream using 'make _routed.hand_crafted.bit'. The resulting bitstream should be equivalent to _routed.bit.