OpenSBI

Clone the repository and add some args to Makefile,

diff --git a/Makefile b/Makefile
index 37793aaf..6224f186 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,8 @@
+# From https://jyywiki.cn/OS/demos/intro/opensbi/Makefile
+export PLATFORM := generic
+export CROSS_COMPILE := riscv64-linux-gnu-
+export DEBUG := 1
+
 #
 # SPDX-License-Identifier: BSD-2-Clause
 #

then let make output the build command.

make -nB > a.log

Use sed to make it more readable (?). This trick also comes from jyy's OS course.

sed -i "s#$(PWD)#.#g" a.log
sed -i "s|mkdir.*echo|echo|g" a.log
sed -i "s/ /\r  /g" a.log

It uses the fw_jump.elf.ld linker script to build the final file.

echo " ELF       platform/generic/firmware/fw_jump.elf"; 
riscv64-linux-gnu-gcc
  ...
  -Wl,-T./build/platform/generic/firmware/fw_jump.elf.ld
  -o
  ./build/platform/generic/firmware/fw_jump.elf

fw_jump.elf.ld is preprocessed fw_jump.elf.ldS.

echo " CPP       platform/generic/firmware/fw_jump.elf.ld"; 
riscv64-linux-gnu-gcc
  ...
  
  -DOPENSBI_DEBUG
  -x
  c
  ./firmware/fw_jump.elf.ldS
  |
  grep -v "#"
  >
  ./build/platform/generic/firmware/fw_jump.elf.ld