How do I compile the kernel without instruction compression？

[cszhouY]

Although I found the option “-mno-relax” is added in Makefile，it doesn't seem to work when I use objdump to read the assembly code.

This is information about my gcc:

riscv64-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=riscv64-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc-cross/riscv64-linux-gnu/9/lto-wrapper
Target: riscv64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 9.4.0-1ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-9/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,gm2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-9 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libitm --disable-libsanitizer --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --without-target-system-zlib --enable-libpth-m2 --enable-multiarch --disable-werror --disable-multilib --with-arch=rv64imafdc --with-abi=lp64d --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=riscv64-linux-gnu --program-prefix=riscv64-linux-gnu- --includedir=/usr/riscv64-linux-gnu/include
Thread model: posix
gcc version 9.4.0 (Ubuntu 9.4.0-1ubuntu1~20.04)

[jrmenzel]

Are you asking about not using compressed 16-bit instructions (C extension in RISC V)?
That is controlled by the flag --with-arch=rv64imafdc - note the c for compressed. Try --with-arch=rv64g (g means imafd).