Commit 5cc12472 authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Masahiro Yamada
Browse files

kbuild: add CONFIG_VMLINUX_MAP expert option 



It can be quite useful to have ld emit a link map file, in order to
debug or verify that special sections end up where they are supposed
to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid
of.

The only reason I'm not just adding this unconditionally is that the
.map file can be rather large (several MB), and that's a waste of
space when one isn't interested in these things. Also make it depend
on CONFIG_EXPERT.

Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
parent 609bbb4d

.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ modules.order 
/linux

/vmlinux

/vmlinux.32

/vmlinux.map

/vmlinux.symvers

/vmlinux-gdb.py

/vmlinuz

Documentation/dontdiff

+1 −0
Original line number Diff line number Diff line
@@ -252,6 +252,7 @@ vmlinux-* 
vmlinux.aout

vmlinux.bin.all

vmlinux.lds

vmlinux.map

vmlinux.symvers

vmlinuz

voffset.h

lib/Kconfig.debug

+10 −0
Original line number Diff line number Diff line
@@ -449,6 +449,16 @@ config VMLINUX_VALIDATION 
	depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT

	default y



config VMLINUX_MAP

	bool "Generate vmlinux.map file when linking"

	depends on EXPERT

	help

	  Selecting this option will pass "-Map=vmlinux.map" to ld

	  when linking vmlinux. That file can be useful for verifying

	  and debugging magic section games, and for seeing which

	  pieces of code get eliminated with

	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.



config DEBUG_FORCE_WEAK_PER_CPU

	bool "Force weak per-cpu definitions"

	depends on DEBUG_KERNEL

scripts/link-vmlinux.sh

+8 −0
Original line number Diff line number Diff line
@@ -155,6 +155,7 @@ vmlinux_link() 
	local output=${1}

	local objects

	local strip_debug

	local map_option



	info LD ${output}
@@ -166,6 +167,10 @@ vmlinux_link() 
		strip_debug=-Wl,--strip-debug

	fi



	if [ -n "${CONFIG_VMLINUX_MAP}" ]; then

		map_option="-Map=${output}.map"

	fi



	if [ "${SRCARCH}" != "um" ]; then

		if [ -n "${CONFIG_LTO_CLANG}" ]; then

			# Use vmlinux.o instead of performing the slow LTO
@@ -187,6 +192,7 @@ vmlinux_link() 
		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}	\

			${strip_debug#-Wl,}			\

			-o ${output}				\

			${map_option}				\

			-T ${lds} ${objects}

	else

		objects="-Wl,--whole-archive			\
@@ -200,6 +206,7 @@ vmlinux_link() 
		${CC} ${CFLAGS_vmlinux}				\

			${strip_debug}				\

			-o ${output}				\

			${map_option:+-Wl,${map_option}}	\

			-Wl,-T,${lds}				\

			${objects}				\

			-lutil -lrt -lpthread
@@ -303,6 +310,7 @@ cleanup() 
	rm -f .tmp_vmlinux*

	rm -f System.map

	rm -f vmlinux

	rm -f vmlinux.map

	rm -f vmlinux.o

}