CMakeLists: Add a RISCV_NONE toolchain

Add a RISCV_NONE toolchain to target an embedded environment. This
allows building libspdm libraries with mbedtls.

Signed-off-by: Alistair Francis <[email protected]>

Author: alistair23

CMakeLists.txt

@@ -89,6 +89,8 @@ if(CMAKE_SYSTEM_NAME MATCHES "Linux")
         MESSAGE("TOOLCHAIN = RISCV_GNU")
     elseif(TOOLCHAIN STREQUAL "RISCV64_GCC")
         MESSAGE("TOOLCHAIN = RISCV64_GCC")
+    elseif(TOOLCHAIN STREQUAL "RISCV_NONE")
+        MESSAGE("TOOLCHAIN = RISCV_NONE")
     elseif(TOOLCHAIN STREQUAL "RISCV_XPACK")
         MESSAGE("TOOLCHAIN = RISCV_XPACK")
     elseif(TOOLCHAIN STREQUAL "ARC_GCC")
@@ -417,6 +419,30 @@ if(CMAKE_SYSTEM_NAME MATCHES "Linux")
 
         SET(CMAKE_C_LINK_EXECUTABLE "<CMAKE_LINKER> <LINK_FLAGS> <OBJECTS> -o <TARGET> -Wl,--start-group <LINK_LIBRARIES> -Wl,--end-group")
 
+    elseif(TOOLCHAIN STREQUAL "RISCV_NONE")
+        SET(CMAKE_C_COMPILER riscv64-elf-gcc)
+        ADD_COMPILE_OPTIONS(-nostdlib -lgcc)
+        if(CMAKE_BUILD_TYPE STREQUAL "Debug")
+           ADD_COMPILE_OPTIONS(-g)
+        endif()
+
+        if(ARCH STREQUAL "riscv32")
+            ADD_COMPILE_OPTIONS(-march=rv32imac_zicsr -mabi=ilp32)
+        elseif(ARCH STREQUAL "riscv64")
+            ADD_COMPILE_OPTIONS(-march=rv64imac_zicsr -mabi=lp64)
+        else()
+            ADD_COMPILE_OPTIONS(-march=error -mabi=error)
+        endif()
+
+        SET(CMAKE_AR riscv64-elf-ar)
+
+        SET(CMAKE_LINKER riscv64-elf-gcc)
+        SET(CMAKE_EXE_LINKER_FLAGS "-no-pie" )
+
+        SET(MBEDTLS_FLAGS -nostdlib -lgcc)
+
+        SET(CMAKE_C_LINK_EXECUTABLE "<CMAKE_LINKER> <LINK_FLAGS> <OBJECTS> -o <TARGET> -Wl,--start-group <LINK_LIBRARIES> -Wl,--end-group")
+
     elseif(TOOLCHAIN STREQUAL "RISCV_XPACK")
         SET(CMAKE_C_COMPILER riscv-none-elf-gcc)
         SET(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "")

README.md

@@ -92,6 +92,7 @@
 | [RISCV_GNU](https://github.com/riscv/riscv-gnu-toolchain) |  -   |  -  |  -  |    -    | riscv32-unknown-linux-gnu-gcc | riscv64-unknown-linux-gnu-gcc |
 | [RISCV64_GCC](https://packages.ubuntu.com/bionic/gcc-riscv64-linux-gnu) |  -   |  -  |  -  |    -    |    -    | riscv64-linux-gnu-gcc |
 | [RISCV_XPACK](https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack) |  -   |  -  |  -  |    -    | riscv-none-elf-gcc | riscv-none-elf-gcc |
+| [RISCV_NONE](https://archlinux.org/packages/extra/x86_64/riscv64-elf-gcc/) |  -   |  -  |  -  |    -    | riscv64-elf-gcc | riscv64-elf-gcc |
 
 ## Documents
 

doc/build.md

@@ -97,6 +97,16 @@ b) [RISCV GNU](https://github.com/riscv-collab/riscv-gnu-toolchain)
 c) [RISCV64 GCC](https://packages.ubuntu.com/bionic/gcc-riscv64-linux-gnu) for RISCV64 only
   - `sudo apt-get install gcc-riscv64-linux-gnu`
 
+d) [RISCV NONE](https://archlinux.org/packages/extra/x86_64/riscv64-elf-gcc/)
+  - Use a [GCC](https://gcc.gnu.org/) compiler configured for building
+    baremetal (not Linux) binaries. This is supported by any modern Linux
+    distro.
+
+  - On Arch it can be installed with
+      ```
+      sudo pacman -Syu riscv32-elf-binutils riscv32-elf-newlib riscv64-elf-binutils riscv64-elf-gcc riscv64-elf-newlib
+      ```
+
 #### Compiler for ARC
 
 a) [ARC GNU](https://github.com/foss-for-synopsys-dwc-arc-processors).
@@ -291,3 +301,14 @@ Unit tests can be disable by adding -DDISABLE_TESTS=1 to CMake.
 ```shell
 -DDISABLE_TESTS=1
 ```
+
+### Embedded builds for RISC-V
+
+The libspdm libraries can be built along with Mbed TLS to target an embedded
+environment. The Integrator must provide a C library and runtime, such as Newlib.
+
+To build libspdm with Mbed TLS for RISC-V 32-bit run the following
+
+```
+cmake -DARCH=riscv32 -DTOOLCHAIN=RISCV_NONE -DTARGET=Debug -DCRYPTO=mbedtls -DDISABLE_TESTS=1 ..
+```