🧪 Use xpack risc-v gcc as default prebuilt toolchain (#1091)

.github/workflows/Processor.yml

@@ -32,30 +32,31 @@ jobs:
     - name: '🧰 Repository Checkout'
       uses: actions/checkout@v4
 
-    - name: '📦 Install RISC-V GCC'
+    - name: '📦 Install xPack RISC-V GCC'
       run: |
-        wget -q https://github.com/stnolting/riscv-gcc-prebuilt/releases/download/rv32i-131023/riscv32-unknown-elf.gcc-13.2.0.tar.gz
+        wget -q https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack/releases/download/v14.2.0-2/xpack-riscv-none-elf-gcc-14.2.0-2-linux-x64.tar.gz
         mkdir $GITHUB_WORKSPACE/riscv-gcc
-        tar -xzf riscv32-unknown-elf.gcc-13.2.0.tar.gz -C $GITHUB_WORKSPACE/riscv-gcc
-        echo $GITHUB_WORKSPACE/riscv-gcc/bin >> $GITHUB_PATH
+        tar -xzf xpack-riscv-none-elf-gcc-14.2.0-2-linux-x64.tar.gz -C $GITHUB_WORKSPACE/riscv-gcc
+        echo $GITHUB_WORKSPACE/riscv-gcc/xpack-riscv-none-elf-gcc-14.2.0-2/bin >> $GITHUB_PATH
 
     - name: '📦 Install GHDL'
       uses: ghdl/setup-ghdl-ci@nightly
 
     - name: '🔍 Check tools'
       run: |
-        riscv32-unknown-elf-gcc -v
+        riscv-none-elf-gcc -v
         ghdl -v
 
     - name: '⚙️ Build Software Framework Tests'
       run: |
-        make -C sw/example/processor_check check
-        make -C sw/example clean_all exe
-        make -C sw/bootloader clean_all info bootloader
+        make RISCV_PREFIX=riscv-none-elf- -C sw/example/processor_check check
+        make RISCV_PREFIX=riscv-none-elf- -C sw/example clean_all exe
+        make RISCV_PREFIX=riscv-none-elf- -C sw/bootloader clean_all info bootloader
 
     - name: '🚧 Compile executable and run simulation'
       run: |
         make -C sw/example/${{ matrix.example }} \
+        RISCV_PREFIX=riscv-none-elf- \
         USER_FLAGS+="-DUART0_SIM_MODE -DUART1_SIM_MODE" \
         clean_all \
         info \

CHANGELOG.md

@@ -29,6 +29,7 @@ mimpid = 0x01040312 -> Version 01.04.03.12 -> v1.4.3.12
 
 | Date | Version | Comment | Ticket |
 |:----:|:-------:|:--------|:------:|
+| 10.11.2024 | 1.10.6.5 | :warning: switch to [xPack](https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack) as default prebuilt RISC-V GCC toolchain (now using `riscv-none-elf-` as default gcc prefix) | [#1091](https://github.com/stnolting/neorv32/pull/1091) |
 | 10.11.2024 | 1.10.6.4 | rework default processor testbench | [#1093](https://github.com/stnolting/neorv32/pull/1093) |
 | 06.11.2024 | 1.10.6.3 | minor rtl edits and cleanups | [#1090](https://github.com/stnolting/neorv32/pull/1090) |
 | 02.11.2024 | 1.10.6.2 | :warning: rework processor boot configuration; add new boot-configuration generics | [#1086](https://github.com/stnolting/neorv32/pull/1086) |

docs/datasheet/software.adoc

@@ -220,7 +220,7 @@ Variables:
   APP_INC        - C include folder(s) [append only]: "-I ."
   APP_SRC        - C source folder(s) [append only]: "./main.c   "
   ASM_INC        - ASM include folder(s) [append only]: "-I ."
-  RISCV_PREFIX   - Toolchain prefix: "riscv32-unknown-elf-"
+  RISCV_PREFIX   - Toolchain prefix: "riscv-none-elf-"
   NEORV32_HOME   - NEORV32 home folder: "../../.."
   GDB_ARGS       - GDB (connection) arguments: "-ex target extended-remote localhost:3333"
   GHDL_RUN_FLAGS - GHDL simulation run arguments: ""

docs/userguide/sw_toolchain_setup.adoc

@@ -2,85 +2,71 @@
 :sectnums:
 == Software Toolchain Setup
 
-To compile (and debug) executables for the NEORV32 a RISC-V toolchain is required.
-There are two possibilities to get this:
+To compile (and debug) executables for the NEORV32 a RISC-V-compatible toolchain is required.
+By default, the project's software framework uses the GNU C Compiler RISC-V port "RISC-V GCC".
+Basically, there are two options to obtain such a toolchain:
 
-1. Download and _build_ the official RISC-V GNU toolchain yourself.
-2. Download and install a prebuilt version of the toolchain; this might also done via the package manager / app store of your OS
+1. Download and _build_ the RISC-V GNU toolchain by yourself.
+2. Download and _install_ a **prebuilt** version of the toolchain.
 
+.Default GCC Prefix
 [NOTE]
-The default toolchain prefix (`RISCV_PREFIX` variable) for this project is **`riscv32-unknown-elf-`**. Of course you can use any other RISC-V
-toolchain (like `riscv64-unknown-elf-`) that is capable to emit code for a `rv32` architecture. Just change `RISCV_PREFIX`
-according to your needs.
+The default toolchain prefix for this project is **`riscv-none-elf-`** (`RISCV_PREFIX` variable).
 
 
-:sectnums:
-=== Building the Toolchain from Scratch
+**Toolchain Requirements**
 
-To build the toolchain by yourself you can follow the guide from the official https://github.com/riscv-collab/riscv-gnu-toolchain GitHub page.
-You need to make sure the generated toolchain fits the architecture of the NEORV32 core. To get a toolchain that even supports minimal
-ISA extension configurations, it is recommend to compile for `rv32i` only. Please note that this minimal ISA also provides further ISA
-extensions like `m` or `c`. Of course you can use a _multilib_ approach to generate toolchains for several target ISAs at once.
+[start=1]
+.The toolchain must be able to emit code for a 32-bit architecture (i.e. `mabi=rv32`).
+.A "bare metal" / stand-alone C standard library should be used (i.e. the no-Linux version; for example "Newlib").
 
-.Preparing GCC build for `rv32i` (minimal ISA)
+.Library/ISA Considerations
+[IMPORTANT]
+Note that a toolchain build with `--with-arch=rv32imc` provides library code (like the C standard library)
+compiled entirely using compressed (`C`) and `mul`/`div` instructions (`M`). Hence, this pre-compiled library
+code CANNOT be executed (without emulation) on an architecture that does not support these ISA extensions.
+
+
+**Building the Toolchain from Scratch**
+
+The official RISC-V GCC GitHub repository (https://github.com/riscv-collab/riscv-gnu-toolchain) provides instructions
+for building the toolchain from scratch:
+
+.Preparing GCC build for `rv32i` (minimal ISA only in this example)
 [source,bash]
 ----
 $ git clone https://github.com/riscv/riscv-gnu-toolchain
 $ cd riscv-gnu-toolchain
-
 $ riscv-gnu-toolchain$ ./configure --prefix=/opt/riscv --with-arch=rv32i --with-abi=ilp32
 $ riscv-gnu-toolchain$ make
 ----
 
-[IMPORTANT]
-Keep in mind that - for instance - a toolchain build with `--with-arch=rv32imc` provides library code (like the C
-standard library) compiled entirely utilizing compressed (`C`) and `mul`/`div` instructions (`M`). Hence, this
-code CANNOT be executed (without emulation) on an architecture that does not support these ISA extensions.
+
+**Downloading and Installing a Prebuilt Toolchain**
+
+Alternatively, a prebuilt toolchain can be used. Some OS package managers provide embedded RISC-V GCC toolchain.
+However, I can highly recommend the toolchain provided by the X-Pack project (MIT license):
+https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack
 
 
-:sectnums:
-=== Downloading and Installing a Prebuilt Toolchain
+**Toolchain Installation**
 
-Alternatively, you can download a prebuilt toolchain.
-
-:sectnums:
-==== Use The Pre-Built Toolchains
-
-We have compiled several GCC toolchains on a 64-bit x86 Ubuntu (Ubuntu on Windows, actually) and uploaded it to
-GitHub. You can directly download the according toolchain archive as single _zip-file_ within a packed
-release from https://github.com/stnolting/riscv-gcc-prebuilt. More information about downloading and installing
-these prebuilt toolchains can be found in the repository's README.
-
-
-:sectnums:
-==== Use a Third Party Toolchain
-
-Of course you can also use any other prebuilt version of the toolchain. There are a lot  RISC-V GCC packages out there -
-even for Windows. On Linux system you might even be able to fetch a toolchain via your distribution's package manager.
-
-[IMPORTANT]
-Make sure the toolchain can (also) emit code for a `rv32i` architecture, uses the `ilp32` or `ilp32e` ABI and **was not build** using
-CPU extensions that are not supported by the NEORV32 (like `D`).
-
-
-:sectnums:
-=== Installation
-
-Now you have the toolchain binaries. The last step is to add them to your `PATH` environment variable (if you have not
-already done so): make sure to add the _binaries_ folder (`bin`) of your toolchain.
+To integrate the toolchain of choice into the NEORV32 software framework, the toolchain's binaries need
+to be added to the system path (e.g. `PATH` environment variable) so they can be used by a shell. Therefore,
+the absolute path to the toolchain's `bin` folder has to be appended to the `PATH` variable:
 
 [source,bash]
 ----
 $ export PATH=$PATH:/opt/riscv/bin
 ----
 
-You should add this command to your `.bashrc` (if you are using bash) to automatically add the RISC-V
+.bashrc
+[TIP]
+This command can be added to `.bashrc` (or similar) to automatically add the RISC-V
 toolchain at every console start.
 
-:sectnums:
-=== Testing the Installation
 
-To make sure everything works fine, navigate to an example project in the NEORV32 example folder and
+To make sure everything works fine, navigate to an example project in the NEORV32 `sw/example` folder and
 execute the following command:
 
 [source,bash]
@@ -89,4 +75,4 @@ neorv32/sw/example/demo_blink_led$ make check
 ----
 
 This will test all the tools required for generating NEORV32 executables.
-Everything is working fine if `Toolchain check OK` appears at the end.
+Everything is working fine if "Toolchain check OK" appears at the end of the log output.

rtl/core/neorv32_package.vhd

@@ -29,7 +29,7 @@ package neorv32_package is
 
   -- Architecture Constants -----------------------------------------------------------------
   -- -------------------------------------------------------------------------------------------
-  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01100604"; -- hardware version
+  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01100605"; -- hardware version
   constant archid_c     : natural := 19; -- official RISC-V architecture ID
   constant XLEN         : natural := 32; -- native data path width
 

sw/common/common.mk

@@ -25,8 +25,8 @@ ASM_INC ?= -I .
 # Optimization
 EFFORT ?= -Os
 
-# Compiler toolchain
-RISCV_PREFIX ?= riscv32-unknown-elf-
+# Compiler toolchain prefix
+RISCV_PREFIX ?= riscv-none-elf-
 
 # CPU architecture and ABI
 MARCH ?= rv32i_zicsr_zifencei

sw/example/dhrystone/README.md

@@ -1,7 +1,9 @@
 ## Dhrystone Benchmark
 
+**:warning: The Dhrystone port is outdated. Have a look at the CoreMark port for benchmarking.**
+
 :copyright: Original sources from [https://github.com/sifive/benchmark-dhrystone](https://github.com/sifive/benchmark-dhrystone);
- see `LICENSE` file. The origianl source code has been modified for the NEORV32 RISC-V Processor.
+ see `LICENSE` file. The original source code has been modified for the NEORV32 RISC-V Processor.
 
 To compile the `main.exe` executable:
 

sw/example/float_corner_test/neorv32_zfinx_extension_intrinsics.h

@@ -54,12 +54,10 @@
 
 #define __USE_GNU
 
-#include <fenv.h>
-//#pragma STDC FENV_ACCESS ON
-
 #define _GNU_SOURCE
 
 #include <float.h>
+#include <fenv.h>
 #include <math.h>
 
 
@@ -130,37 +128,6 @@ uint32_t get_hw_exceptions(void) {
 }
 
 
-/**********************************************************************//**
- * Get exception flags from C runtime (floating-point emulation).
- *
- * @warning WORK-IN-PROGRESS!
- *
- * @return Floating point exception status word.
- **************************************************************************/
-uint32_t get_sw_exceptions(void) {
-
-  const uint32_t FP_EXC_NV_C = 1 << 0; // invalid operation
-  const uint32_t FP_EXC_DZ_C = 1 << 1; // divide by zero
-  const uint32_t FP_EXC_OF_C = 1 << 2; // overflow
-  const uint32_t FP_EXC_UF_C = 1 << 3; // underflow
-  const uint32_t FP_EXC_NX_C = 1 << 4; // inexact
-
-  int fpeRaised = fetestexcept(FE_ALL_EXCEPT);
-
-  uint32_t res = 0;
-
-  if (fpeRaised & FE_INVALID)   { res |= FP_EXC_NV_C; }
-  if (fpeRaised & FE_DIVBYZERO) { res |= FP_EXC_DZ_C; }
-  if (fpeRaised & FE_OVERFLOW)  { res |= FP_EXC_OF_C; }
-  if (fpeRaised & FE_UNDERFLOW) { res |= FP_EXC_UF_C; }
-  if (fpeRaised & FE_INEXACT)   { res |= FP_EXC_NX_C; }
-
-  feclearexcept(FE_ALL_EXCEPT);
-
-  return res;
-}
-
-
 // ################################################################################################
 // "Intrinsics"
 // ################################################################################################

sw/example/makefile

@@ -6,8 +6,8 @@ TOPTARGETS := exe clean_all check info all
 SUBDIRS := $(wildcard */.)
 # ignore dummy folders (starting with '~')
 EXCLDIR := $(wildcard ~*/.)
-# ignore the Eclipse project
-EXCLDIR += eclipse/.
+# ignore some of the default projects/examples
+EXCLDIR += eclipse/. dhrystone/. performance_tests/. float_corner_test/.
 SUBDIRS := $(filter-out $(EXCLDIR), $(SUBDIRS))
 
 $(TOPTARGETS): $(SUBDIRS)