Update tools and docs and tool skeleton

ref_app/target/micros/wch_ch32v307/make/wch_ch32v307_flags.gmk

@@ -8,10 +8,10 @@
 # compiler flags for the target architecture
 # ------------------------------------------------------------------------------
 
-GCC_TARGET   := riscv32-unknown-elf
-GCC_PREFIX   := riscv32-unknown-elf
+GCC_TARGET   := riscv-none-elf
+GCC_PREFIX   := riscv-none-elf
 
-GCC_VERSION  := 13.2.0
+GCC_VERSION  := 14.2.0
 
 TGT_SUFFIX    = elf
 

ref_app/tools/AVR/avrdude/avrdude-v8.0-windows-x64/readme.md

@@ -7,8 +7,8 @@ building the reference application `ref_app`, will be found in the `bin` directo
 These instructions are for modern `Win*`.
 
 The programming device being used is the AVRISP mkII, which is an older USB-based
-programmer. Drivers can be installed along with with ATMEL(R) Studio or alternative
-open source USB driver-options are available.
+programmer. Drivers can be installed along with with ATMEL(R) Studio.
+Also alternative open source USB driver-options are available.
 
 ## Getting Started
 

ref_app/tools/Util/msys64/usr/bin/_readme_GnuTools.txt

@@ -0,0 +1,26 @@
+Update 2024-01-31
+
+- Simply use tools from "UnxUtils" including
+  echo, mkdir, rm, sed. See also:
+  https://sourceforge.net/projects/unxutils
+
+- The make.exe stays the same as the one below.
+
+- Begin building cross-compilers on msys2
+  with a completely standalone, static MinGW
+  (from nuwen). These do not require and DLLs.
+
+-------------------------------------------------------
+
+- The source of echo, mkdir, rm, sed is mingw64/msys2.
+- Their associated DLLs msys-2.0, msys-iconv-2 and
+  msys-intl-8 are taken from mingw64/msys2.
+
+- GCC toolchains are in the "local" directory and
+  its subdirectories. The DLL libwinpthread-1
+  is needed for these GCC ports. This DLL has
+  also been taken from mingw64/msys2.
+
+- The make.exe program GNUmake 4.2.1 built for Windows
+  with MSVC 14.2. See also the repository for this ar:
+  https://github.com/ckormanyos/real-time-cpp-toolchains

ref_app/tools/Util/msys64/usr/local/README.md

@@ -0,0 +1,13 @@
+real-time-cpp-toolchains - Individual Toolchains
+==================
+
+| GCC target             | location              |
+| ---------------------- | --------------------- |
+| `arm-none-eabi`        | [ARM(R) GNU Toolchain](https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads)                  |
+| `avr`                  | [ckormanyos/avr-gcc-build](https://github.com/ckormanyos/avr-gcc-build)                                    |
+| `riscv-none-elf`       | [xpack-dev-tools/riscv-none-elf-gcc-xpack](https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack)    |
+| `rl78-unknown-elf`     | [ckormanyos/gcc-rl78-unknown-elf](https://github.com/ckormanyos/gcc-rl78-unknown-elf)                      |
+| `rx-elf`               | [ckormanyos/gcc-rx-elf](https://github.com/ckormanyos/gcc-rx-elf)                                          |
+| `v850-unknown-elf`     | [ckormanyos/gcc-v850-unknown-elf](https://github.com/ckormanyos/gcc-v850-unknown-elf)                      |
+| `x86_64-w64-mingw32`   | [nuwen distro](https://nuwen.net/mingw.html)                                                               |
+| `xtensa-esp32-elf`     | [espressif/crosstool-NG](https://github.com/espressif/crosstool-NG)                                        |

ref_app/tools/Util/msys64/usr/local/gcc-13.2.0-rl78-unknown-elf/README.md

@@ -0,0 +1,5 @@
+`gcc-rl78-unknown-elf`
+==================
+
+See also
+[ckormanyos/gcc-rl78-unknown-elf](https://github.com/ckormanyos/gcc-rl78-unknown-elf)

ref_app/tools/Util/msys64/usr/local/gcc-13.2.0-rx-elf/README.md

@@ -0,0 +1,5 @@
+`gcc-rx-elf`
+==================
+
+See also
+[ckormanyos/gcc-rx-elf](https://github.com/ckormanyos/gcc-rx-elf)

ref_app/tools/Util/msys64/usr/local/gcc-13.2.0-v850-unknown-elf/README.md

@@ -0,0 +1,5 @@
+`gcc-v850-unknown-elf`
+==================
+
+See also
+[ckormanyos/gcc-v850-unknown-elf](https://github.com/ckormanyos/gcc-v850-unknown-elf)

ref_app/tools/Util/msys64/usr/local/gcc-13.2.0-x86_64-w64-mingw32/README.md

@@ -0,0 +1,5 @@
+`gcc-x86_64-w64-mingw32`
+==================
+
+See also
+[nuwen distro](https://nuwen.net/mingw.html)

ref_app/tools/Util/msys64/usr/local/gcc-13.2.0-xtensa-esp32-elf/README.md

@@ -0,0 +1,7 @@
+`gcc-xtensa-esp32-elf`
+==================
+
+See also the releases at
+[espressif/crosstool-NG](https://github.com/espressif/crosstool-NG),
+for example
+[release 13.2](https://github.com/espressif/crosstool-NG/releases/tag/esp-13.2.0_20230928)

ref_app/tools/Util/msys64/usr/local/gcc-13.3.1-arm-none-eabi/README.md

@@ -0,0 +1,5 @@
+`gcc-arm-none-eabi`
+==================
+
+See also the toolchains at
+[ARM(R) GNU Toolchain](https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads)

ref_app/tools/Util/msys64/usr/local/gcc-14.2.0-avr/README.md

@@ -0,0 +1,5 @@
+`avr-gcc`
+==================
+
+See also
+[ckormanyos/avr-gcc-build](https://github.com/ckormanyos/avr-gcc-build)

ref_app/tools/Util/msys64/usr/local/gcc-14.2.0-riscv-none-elf/README.md

@@ -0,0 +1,5 @@
+`riscv-none-elf`
+==================
+
+See also
+[xpack-dev-tools/riscv-none-elf-gcc-xpack](https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack)