text: #! /bin/bash -e
  
  OVERLAY="$1"
  NAME="$2"
  FREQ=40000
  BASE=$(dirname "$0")
  TARGET="$BASE"/core-$NAME
  
  [ $# -ge 2 -a -f "$OVERLAY" ] || { cat <<EOF
  Usage: $0 overlay-archive-to-import core-name [frequency-in-KHz]
      overlay-archive-to-import:  file name of xtensa-config-overlay.tar.gz
                                  to import configuration from.
      core-name:                  QEMU name of the imported core. Must be valid
                                  C identifier.
      frequency-in-KHz:           core frequency (40MHz if not specified).
  EOF
  exit
  }
  
  [ $# -ge 3 ] && FREQ="$3"
  mkdir -p "$TARGET"
  tar -xf "$OVERLAY" -C "$TARGET" --strip-components=1 \
      --xform='s/core/core-isa/' config/core.h
  tar -xf "$OVERLAY" -O gdb/xtensa-config.c | \
      sed -n '1,/*\//p;/XTREG/,/XTREG_END/p' > "$TARGET"/gdb-config.c
  
  cat <<EOF > "${TARGET}.c"
  #include "cpu.h"
  #include "exec/exec-all.h"
  #include "exec/gdbstub.h"
  #include "qemu/host-utils.h"
  
  #include "core-$NAME/core-isa.h"
  #include "overlay_tool.h"
  
  static XtensaConfig $NAME __attribute__((unused)) = {
      .name = "$NAME",
      .gdb_regmap = {
          .reg = {
  #include "core-$NAME/gdb-config.c"
          }
      },
      .clock_freq_khz = $FREQ,
      DEFAULT_SECTIONS
  };
  
  REGISTER_CORE($NAME)
  EOF
  
  grep -q core-${NAME}.o "$BASE"/Makefile.objs || \
      echo "obj-y += core-${NAME}.o" >> "$BASE"/Makefile.objs
  