- Building binutils, gcc, and gdb: link.
- See the section "Roll-your-own".
- Page with a nice table of available targets: link.
- Comments on examining gcc's IR with the "-fdump-tree-all" and '-fdump-rtl-all" options: link.
- Useful clang commands.
- Generate assembly:
- clang -S ./helloworld.c -target x86
- Emit LLVM intermediate code:
- clang -S -emit-llvm ./helloworld.c -o ./helloworld.s
- Compile LLVM intermediate code into assembly code:
- llc -march x86 ./helloworld.s
- Use binutils to generate object file:
- as ./helloworld.s -o helloworld.o
- Or gcc to generate executable:
- gcc ./helloworld.s -o helloworld
- Command for disassembling object file:
- objdump -d helloworld.o
- Command to extract text from object file:
-
objcopy -O binary --only-section=.text /path/firmware.ko /content.bin
Update 9 Aug. 2016.
I realized it could be useful to explain here how to generate a MIPS binary.
The MIPS assembly can be generated using the clang command above:
- clang -S ./helloworld.c -target mips -o helloworld.s
To generate a MIPS binary, we can build binutils for MIPS.
- Download latest binutils from here: link.
- Then (assuming you are on version 2.27 of binutils):
- tar xzvf binutils-2.27
- mkdir build-binutils
- cd build-binutils
- ../binutils-2.27/configure --TARGET=mips-el-unknown-linux-gnu --prefix=<installpath>
- make
- make install
- helloworld.s can be assembled like this:
- <installpath>/mipsel-unknown-linux-gnu-as helloworld.s -o helloworld
- You can examine the contents of the output file using the built objdump, as described above:
- <installpath>/mipsel-unknown-linux-gnu-objdump -d helloworld
- And extract the text:
- <installpath>/mipsel-unknown-linux-gnu-objcopy -O helloworld --only-section=.text ./helloworld helloworld.text
Much of the above was taken from here: link.
