Linux kernel tip: build with custom CFLAGS

Build linux kernel, either whole or a selected directory with compiler flags, without editing any Makefiles or such. cd linux.git make ccflags-y = '-Wundef' kernel/ Any change to flags will be detected and leads to full rebuild of all affected files. Building whole directory must have the trailing / . Whole modules can be built with M=fs/btrfs , where M= does not require the trailing / . What to…