linux-stable/arch/x86/purgatory/Makefile

purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o string.o

targets += $(purgatory-y)
PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))

LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib
targets += purgatory.ro

# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
# in turn leaves some undefined symbols like __fentry__ in purgatory and not
# sure how to relocate those. Like kexec-tools, use custom flags.

KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin -ffreestanding -c -MD -Os -mcmodel=large
KBUILD_CFLAGS += -m$(BITS)

$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
		$(call if_changed,ld)

targets += kexec-purgatory.c

quiet_cmd_bin2c = BIN2C   $@
      cmd_bin2c = cat $(obj)/purgatory.ro | $(objtree)/scripts/basic/bin2c kexec_purgatory > $(obj)/kexec-purgatory.c

$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
	$(call if_changed,bin2c)


obj-$(CONFIG_KEXEC_FILE)	+= kexec-purgatory.o