Notes for the 2025_06_24_12.12 version:

  Before starting the build, you may need to install some packages.
  Eventually I'll add this to the build script, but for now do this:

  sudo apt install make build-essential libncurses-dev bison flex libssl-dev libelf-dev gcc-aarch64-linux-gnu

  In order to load the PL, I wrote a script "load_fpga.sh".
  Unfortunately, I only put it in the RFSoC4x2 files, when it is
  universally applicable for other boards and other FPGAs.  I'll move
  it eventually, but for now you'll have to dig it out of the RFSoC4x2
  files if you want to use it for another board.

  Xilinx's Vivado/Vitis tools must be installed to make some pieces build.
  Vivado2024.2 is tested, but probably almost any recent version will work.

  The script to create the Debian filesystem looks for
  "/usr/bin/qemu-arm64-static".  On older machines, this is only
  available as "/usr/bin/qemu-aarch64-static".  It's the same program.
  The easiest fix is to edit build.sh in the filesystem directory to
  change it.  (Which I'll do eventually.)
  
  Getting ethernet working requires a "PHY" address, which is an
  address hard-configured into an ethernet controller chip external to
  the FPGA.  This PHY address is not something that Vivado accepts as
  a ZYNQ configuration option.  So supporting this will require an
  additional configuration file besides the XSA and some additional
  instructions.  (Or alternately, modifying the ethernet driver so
  that if the PHY address isn't specified the driver probes for it.)

  This raises the question of whether there are additional
  configuration items that are needed but that aren't captured in the
  Vivado ZYNQ configuration.  On the ZCU111 there is an additional
  ethernet reset line that could be configured, but configuring it
  appears to be nonessential.  So the ethernet PHY address is the only
  neccessary configuration item that's not in the XSA, on the two boards
  looked at so far.