doc: add more notices about 0.5.0 release changes

- Including toolchain support update
- Including how to contribute and port your own target

Signed-off-by: Huaqi Fang <[email protected]>

doc/source/changelog.rst

@@ -27,7 +27,7 @@ This is release version ``0.5.0`` of Nuclei SDK.
   - Add cpuinfo case to dump nuclei cpu feature
   - Add stack check demo to demostrate nuclei stack check feature
   - Add support for gcc13/clang17/terapines/iar compiler
-  - Fix missing break in ``__set_hpm_event`` function
+  - Fix missing break in ``__set_hpm_event`` function, take care if you are using this API.
   - For different compiler option support, we introduced ``toolchain_$(TOOLCHAIN).mk`` file to place toolchain specified options, see benchmark examples' Makefile
   - Optimize demo_cidu smp case
   - Optimize application code and makefile when port for clang, terapines zcc and iar compiler
@@ -53,7 +53,7 @@ This is release version ``0.5.0`` of Nuclei SDK.
 
 * SOC
 
-  - Demosoc support is removed since evalsoc is the successor
+  - **CAUTION**: Demosoc support is removed since evalsoc is the successor, please use **evalsoc** now.
   - Set RUNMODE_CCM_EN macro when CCM_EN make variable passed and allow __CCM_PRESENT overwrite by RUNMODE_CCM_EN macro
   - Enable __CIDU_PRESENT macro passed via compiler option
   - Update cpu startup asm code to fix clang compile issue such as STB_WEAK warning and non-ABS relocation error

doc/source/contribute.rst

@@ -20,6 +20,12 @@ Port your Nuclei SoC into Nuclei SDK
 If you want to port you Nuclei Processor Core based Board to Nuclei SDK,
 you need to follow these steps:
 
+And the best example is our evalsoc support, although it may contains many unused features you may
+not want to use, but it is our evaluation SoC and will supply to provide best support for Nuclei RISC-V
+CPU features, if you are already using it, please keep in update of the evalsoc support changes in each
+release, you can track it by diff each release changes, and please also remember Nuclei SDK release may
+also bump with NMSIS release.
+
 Assume your SoC name is ``ncstar``, based on Nuclei core **n307**, and **RISCV_ARCH**
 is ``rv32imafc``, **RISCV_ABI** is ``ilp32f``, and you made a new board called ``ncstar_eval``,
 and this SoC only support **FlashXIP** download mode.

doc/source/develop/buildsystem.rst

@@ -560,9 +560,9 @@ TOOLCHAIN
 This variable is used to select different toolchain to compile application.
 Currently we support 3 toolchain in Nuclei SDK.
 
-* **nuclei_gnu**: default, it will choose nuclei gnu toolchain.
-* **nuclei_llvm**: still in experiment, nuclei customized extensions not yet supported.
-* **terapines**: still in experiment, it depends on the toolchain vendor about the supported extensions.
+* **nuclei_gnu**: default, it will choose nuclei gnu toolchain, distributed with Nuclei Toolchain.
+* **nuclei_llvm**: still in experiment, nuclei customized extensions not yet supported, distributed with Nuclei Toolchain.
+* **terapines**: still in experiment, it depends on the toolchain vendor about the supported extensions, if you want to take a try with it, just visit https://www.terapines.com/ and request an terapines toolchain evaluation.
 
 For **nuclei_gnu/nuclei_llvm** toolchain both newlib and libncrt library are supported,
 but nuclei_llvm toolchain multilib selection mechanism is not as good as gnu toolchain,
@@ -571,6 +571,8 @@ you need to take care of the arch isa string order, please see ``riscv64-unknown
 And IAR compiler support is also done in Nuclei SDK, you can take a try with it
 via ``ideprojects/iar`` folder provided prebuilt ide projects.
 
+If you want to use old Nuclei GNU Toolchain <= 2022.12 in Nuclei SDK 0.5.0, you need to pass extra ``COMPILE_PREFIX=riscv-nuclei-elf-`` when build any application, such as ``make CORE=n307fd COMPILE_PREFIX=riscv-nuclei-elf-  STDCLIB=libncrt_small clean all``, but this is not recommended, and will be deprecated in future any time.
+
 .. _develop_buildsystem_var_download:
 
 DOWNLOAD
@@ -1146,6 +1148,11 @@ system libraries by the ``STDCLIB`` variable choice, so need to link desired lib
 
 .. note::
 
+    * For clang based compiler, if ``-u _print_float`` is not passed in linker options, it may fail
+      during link process, so here we pass ``-u _print_float`` for newlib_nano, then it means for
+      nuclei_llvm and terapines toolchain, ``STDCLIB=newlib_nano`` equals to ``STDCLIB=newlib_small``
+    * Nuclei libncrt library couldn't be used with terapines toolchain, so you can't use any libncrt library
+      when you are using terapines toolchain.
     * About Newlib and Newlib nano difference, please check
       https://github.com/riscv-collab/riscv-newlib/blob/riscv-newlib-3.2.0/newlib/README
     * About Nuclei C runtime library, it provided basic libgcc, c library and math library feature, but