doc: Update toolchain build doc
Change-Id: I44acf6b308b28e76a293e8d88bd48840a33d38eb
diff --git a/BuildRiscVToolchain.md b/BuildRiscVToolchain.md
index fef1138..0f91330 100644
--- a/BuildRiscVToolchain.md
+++ b/BuildRiscVToolchain.md
@@ -5,6 +5,7 @@
libraries, and LLVM to build the compiler, linker, and utility tools.
## Prerequisites
+
Your host machine needs to have the following packages installed, which are
already part of the Shodan prerequisite pacakges
@@ -13,16 +14,18 @@
* Clang
The source code of the toolchain is at
+
* [riscv-gnu-toolchain](https://github.com/riscv/riscv-gnu-toolchain): Checkout
-the latest release tag, and checkout the submodule `riscv-binutils` with the
-`rvv-1.0.x-zfh` branch.
+the latest release tag, and checkout the submodule `riscv-binutils` at the master
+branch at git://sourceware.org/git/binutils-gdb.git
* [llvm-project](https://github.com/llvm/llvm-project): Checkout the latest green
commit
## Build RISC-V Linux toolchain (64-bit)
-### Build GCC:
-```
+### Build GCC
+
+```bash
$ mkdir -p <GCC_BUILD_PATH>
$ cd <GCC_BUILD_PATH>
$ <GCC_SRC_PATH>/configure \
@@ -33,79 +36,88 @@
--with-cmodel=medany
$ make -C <GCC_BUILD_PATH> linux
```
+
Notice Linux requires the full general CPU extension support, i.e., rv64imafdc,
and the ABI also needs to support hard double-float modules. For 32-bit Linux,
build the toolchain with the flags of `--with-arch=rv32gc --with-abi=ilp32d`.
-### Build LLVM:
-```
+### Build LLVM
+
+```bash
$ cmake -B <LLVM_BUILD_PATH> \
- -DCMAKE_INSTALL_PREFIX=<TOOLCHAIN_OUT_DIR> \
- -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ \
- -DCMAKE_BUILD_TYPE=Release \
- -DLLVM_TARGETS_TO_BUILD="RISCV" \
- -DLLVM_ENABLE_PROJECTS="clang" \
- -DLLVM_DEFAULT_TARGET_TRIPLE="riscv64-unknown-linux-gnu" \
- -DLLVM_INSTALL_TOOLCHAIN_ONLY=On \
- -DDEFAULT_SYSROOT=../sysroot \
- -G Ninja \
- <LLVM_SRC_PATH>/llvm
+ -DCMAKE_INSTALL_PREFIX=<TOOLCHAIN_OUT_DIR> \
+ -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ \
+ -DCMAKE_BUILD_TYPE=Release \
+ -DLLVM_TARGETS_TO_BUILD="RISCV" \
+ -DLLVM_ENABLE_PROJECTS="clang" \
+ -DLLVM_DEFAULT_TARGET_TRIPLE="riscv64-unknown-linux-gnu" \
+ -DLLVM_INSTALL_TOOLCHAIN_ONLY=On \
+ -DDEFAULT_SYSROOT=../sysroot \
+ -G Ninja \
+ <LLVM_SRC_PATH>/llvm
$ cmake --build <LLVM_BUILD_PATH> --target install
```
+
For 32-bit, change the LLVM target triple to `riscv32-unknown-linux-gnu`.
## Build RISC-V bare-metal toolchain (32-bit)
-### Build GCC:
-```
+### Build 32-bit GCC
+
+```bash
$ mkdir -p <GCC_BUILD_PATH>
$ cd <GCC_BUILD_PATH>
$ <GCC_SRC_PATH>/configure \
--srcdir=<GCC_SRC_PATH> \
--prefix=<TOOLCHAIN_OUT_DIR> \
- --with-arch=rv32gc \
+ --with-arch=rv32i2p0mf2p0 \
--with-abi=ilp32 \
--with-cmodel=medany
$ make -C <GCC_BUILD_PATH> newlib
```
+
Notice for bare-metal newlib there's no hard constraints on CPU feature and ABI
support. However, LLVM for bare-metal only supports soft-float modules, so the
-GCC ABI setting needs to match that.
+GCC ABI setting needs to match that. Also, the ISA version needs to be specified,
+since binuils ISA supports 20191213 spec and LLVM is at v2.2 spec
-### Build LLVM:
-```
+### Build 32-bit LLVM
+
+```bash
$ cmake -B <LLVM_BUILD_PATH> \
- -DCMAKE_INSTALL_PREFIX=<TOOLCHAIN_OUT_DIR> \
- -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ \
- -DCMAKE_BUILD_TYPE=Release \
- -DLLVM_TARGETS_TO_BUILD="RISCV" \
- -DLLVM_ENABLE_PROJECTS="clang" \
- -DLLVM_DEFAULT_TARGET_TRIPLE="riscv32-unknown-elf" \
- -DLLVM_INSTALL_TOOLCHAIN_ONLY=On \
- -DDEFAULT_SYSROOT=../riscv32-unknown-elf \
- -G Ninja \
- <LLVM_SRC_PATH>/llvm
+ -DCMAKE_INSTALL_PREFIX=<TOOLCHAIN_OUT_DIR> \
+ -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ \
+ -DCMAKE_BUILD_TYPE=Release \
+ -DLLVM_TARGETS_TO_BUILD="RISCV" \
+ -DLLVM_ENABLE_PROJECTS="clang" \
+ -DLLVM_DEFAULT_TARGET_TRIPLE="riscv32-unknown-elf" \
+ -DLLVM_INSTALL_TOOLCHAIN_ONLY=On \
+ -DDEFAULT_SYSROOT=../riscv32-unknown-elf \
+ -G Ninja \
+ <LLVM_SRC_PATH>/llvm
$ cmake --build <LLVM_BUILD_PATH> --target install
```
+
#### Build compiler-rt
This should not be necessary for the Shodan usage, but in case the compiler-rt
-builtins is required in the project, it can be built with the additional commands
+builtins is required in the project (instead of using libgcc), it can be built
+with the additional commands:
-```
+```bash
$ export PATH=<TOOLCHAIN_OUT_DIR>/bin:${PATH}
-$ cmake -B <LLVM_BUILD_PATH>/compiler-rt
+$ cmake -B <LLVM_BUILD_PATH>/compiler-rt \
-DCMAKE_INSTALL_PREFIX=$PREFIX \
-DCMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY \
-DCMAKE_AR=<TOOLCHAIN_OUT_DIR>/bin/llvm-ar \
-DCMAKE_NM=<TOOLCHAIN_OUT_DIR>/bin/llvm-nm \
-DCMAKE_RANLIB=<TOOLCHAIN_OUT_DIR>/bin/llvm-ranlib \
- -DCMAKE_C_FLAGS="-march=rv32gc" \
- -DCMAKE_ASM_FLAGS="-march=rv32gc" \
+ -DCMAKE_C_FLAGS="-march=rv32i2p0mf2p0v1p0" \
+ -DCMAKE_ASM_FLAGS="-march=rv32i2p0mf2p0v1p0" \
-DCMAKE_C_COMPILER=<TOOLCHAIN_OUT_DIR>/bin/clang \
-DCMAKE_C_COMPILER_TARGET=riscv32-unknown-elf \
-DCMAKE_ASM_COMPILER_TARGET=riscv32-unknown-elf \
- -DCOMPILER_RT_OS_DIR="clang/13.0.0/lib" \
+ -DCOMPILER_RT_OS_DIR="clang/14.0.0/lib" \
-DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld" \
-DCOMPILER_RT_BUILD_BUILTINS=ON \
-DCOMPILER_RT_BUILD_SANITIZERS=OFF \
@@ -116,19 +128,21 @@
-DCOMPILER_RT_BAREMETAL_BUILD=ON \
-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON \
-DLLVM_CONFIG_PATH=<LLVM_BUILD_PATH>/bin/llvm-config \
- -DCMAKE_C_FLAGS="-march=rv32gc -mno-relax" \
- -DCMAKE_ASM_FLAGS="-march=gv32gc -mno-relax" \
+ -DCMAKE_C_FLAGS="-march=rv32i2p0mf2p0v1p0 -mno-relax" \
+ -DCMAKE_ASM_FLAGS="-march=rv32i2p0mf2p0v1p0 -mno-relax" \
-G "Ninja" <LLVM_SRC_PATH>/compiler-rt
$ cmake --build <LLVM_BUILD_PATH>/compiler-rt --target install
```
### Build newlib
-The source code is at https://github.com/riscv/riscv-newlib
+Even with compiler_rt to replace libgcc, we still need to build libc, libm, and
+libgloss as the toolchain prebuilts. They can also be built with clang
+The source code is at <https://github.com/riscv/riscv-newlib>
***NOTE: The GCC utility tools needs to be built first.***
-```
+```bash
$ mkdir -p <NEWLIB_BUILD_PATH>
$ cd <NEWLIB_BUILD_PATH>
$ <NEWLIB_SRC_PATH>/configure \
@@ -140,23 +154,29 @@
--enable-newlib-register-fini \
CC_FOR_TARGET=clang \
CXX_FOR_TARGET=clang++ \
- CFLAGS_FOR_TARGET="-march=rv32gc -O2 -D_POSIX_MODE -mno-relax" \
- CXXFLAGS_FOR_TARGET="-march=rv32gc -O2 -D_POSIX_MODE -mno-relax"
+ CFLAGS_FOR_TARGET="-march=rv32i2p0mf2p0v1p0 -O2 -D_POSIX_MODE -mno-relax" \
+ CXXFLAGS_FOR_TARGET="-march=rv32i2p0mf2p0v1p0 -O2 -D_POSIX_MODE -mno-relax"
$ make -j32
$ make install
```
+
+The newlib nano spec needs to be built separatedly and then merged with newlib.
+GNU top-level Makefile lists the flags to build nano and the merging script.
+
## Test toolchain
Run
-```
+
+```bash
<TOOLCHAIN_OUT_DIR>/bin/<arch>-<os>-<abi>-gcc -v
```
+
to see the supported ABIs, architectures, library paths, etc.
Try to compile a simple c code (copied from CMake's package content, e.g.,
`/usr/share/cmake-3.18/Modules/CMakeTestCCompiler.cmake`)
-```
+```c
#ifdef __cplusplus
# error "The CMAKE_C_COMPILER is set to a C++ compiler"
#endif
@@ -169,11 +189,13 @@
#endif
{ (void)argv; return argc-1;}
```
+
To build (32-bit bare-metal example)
+```bash
+$<TOOLCHAIN_OUT_DIR>/bin/clang -c testCCompiler.c -O --target=riscv32
+$<TOOLCHAIN_OUT_DIR>/bin/riscv32-unknown-elf-gcc testCCompiler.o -o testCCompiler -march=rv32gc -mabi=ilp32
```
-$ <TOOLCHAIN_OUT_DIR>/bin/clang -c testCCompiler.c -O --target=riscv32
-$ <TOOLCHAIN_OUT_DIR>/bin/riscv32-unknown-elf-gcc testCCompiler.o -o testCCompiler -march=rv32gc -mabi=ilp32
-```
+
You can also use `readelf` to inspect the object file before building the binary
to see if the architecture and ABI match.
