Building Linux

Some notes about building the Linux kernel.

Vanilla

Build with warnings:

make -j4 W=1

To build with clang:

make -j4 W=1 ARCH=x86_64 HOSTCC=clang CC=clang

Cross compile:

make -j4 ARCH=x86_64 CROSS_COMPILE=/usr/bin/x86_64-pc-linux-gnu-

Tuxmake

If you just want to build the kernel and you don’t want to deal with dependencies, tuxmake is a great tool for this.

You can go yo the kernel root directory and simply run tuxmake to build it. You can specify some configuration flags. Tuxmake will download a docker container for the build and configure the toolchain and .config based on the falgs.

cd linux
tuxmake

# or
tuxmake --target-arch=arm64 \
        --toolchain=gcc-10  \
        --kconfig-add /path/to/my.config

Build Configs

Some build configs you should know about:

• CONFIG_KASAN=y CONFIG_KASAN_GENERIC=y #CONFIG_KASAN_SW_TAGS=y #CONFIG_KASAN_HW_TAGS=y CONFIG_KASAN_VMALLOC=y

  Enable the generic kernel address sanitization, then pick the one you want.

• CONFIG_UBSAN=y

  Enable runtime undefined behaviour checker.

• CONFIG_LOCKDEP=y

  Catch deadlocks

• CONFIG_DEBUG_VM=y

  Do this when touching memory management or DMA.

• CONFIG_PROVE_RCU=y

  This ensures you are accessing RCU-protected memory properly

• CONFIG_SLUB_DEBUG_ON=y

  Do more checks on the slab allocator

• CONFIG_DEBUG_STACKOVERFLOW=y

  Check that we did not put huge object on the stack, because it is very limited.

• CONFIG_DETECT_HUNG_TASK=y

  If you accidentally put a process into an uninterruptible sleep, this will dump the stack trace