On Fri, Nov 11, 2016 at 12:23:25PM +0100, Jiri Slaby wrote: > Hi, > > I am trying a new gcc with new warnings enabled: > > make O=../a/gcc7/ CC='gcc-7' V=1 kernel/exit.o > EXTRA_CFLAGS='-Wimplicit-fallthrough=3' > > But the build fails when building under tools/: > ... > make -f /home/latest/linux/tools/build/Makefile.build dir=. obj=fixdep > gcc > -Wp,-MD,/home/latest/a/gcc7/tools/objtool/.exec-cmd.o.d,-MT,/home/latest/a/gcc7/tools/objtool/exec-cmd.o > -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security > -Wformat-y2k -Winit-self -Wmissing-declarations -Wmissing-prototypes > -Wnested-externs -Wno-system-headers -Wold-style-definition -Wpacked > -Wredundant-decls -Wshadow -Wstrict-aliasing=3 -Wstrict-prototypes > -Wswitch-default -Wswitch-enum -Wundef -Wwrite-strings -Wformat > -Wimplicit-fallthrough=3 -ggdb3 -Wall -Wextra -std=gnu99 -O6 > -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fPIC -Werror > -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE > -I/home/latest/linux/tools/include/ -I/home/latest/linux/include/uapi > -I/home/latest/linux/include -D"BUILD_STR(s)=#s" -c -o > /home/latest/a/gcc7/tools/objtool/exec-cmd.o exec-cmd.c > gcc: error: unrecognized command line option ‘-Wimplicit-fallthrough=3’; > did you mean ‘-Wno-fallthrough’? > > > Apparently, CC is not respected for tools/ dir. > > Well, it is used (tools/build/Makefile.build): > # Compile command > quiet_cmd_cc_o_c = CC $@ > cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< > > > But I don't know why CFLAGS propagate from Makefile to tools/, but CC > doesn't (both are exported)? Any ideas? so the root Makefile assign CC directly: CC = $(CROSS_COMPILE)gcc we are trying to be a little bit smarter in perf and set it only if it's not set by user # Allow setting CC and AR and LD, or setting CROSS_COMPILE as a prefix. $(call allow-override,CC,$(CROSS_COMPILE)gcc) $(call allow-override,AR,$(CROSS_COMPILE)ar) $(call allow-override,LD,$(CROSS_COMPILE)ld) I did not check the other tools.. thanks, jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
