linux-imx/kernel/Makefile
Masahiro Yamada 46b41d5dd8 kbuild: update config_data.gz only when the content of .config is changed
If the timestamp of the .config file is updated, config_data.gz is
regenerated, then vmlinux is re-linked. This occurs even if the content
of the .config has not changed at all.

This issue was mitigated by commit 67424f61f8 ("kconfig: do not write
.config if the content is the same"); Kconfig does not update the
.config when it ends up with the identical configuration.

The issue is remaining when the .config is created by *_defconfig with
some config fragment(s) applied on top.

This is typical for powerpc and mips, where several *_defconfig targets
are constructed by using merge_config.sh.

One workaround is to have the copy of the .config. The filechk rule
updates the copy, kernel/config_data, by checking the content instead
of the timestamp.

With this commit, the second run with the same configuration avoids
the needless rebuilds.

  $ make ARCH=mips defconfig all
   [ snip ]
  $ make ARCH=mips defconfig all
  *** Default configuration is based on target '32r2el_defconfig'
  Using ./arch/mips/configs/generic_defconfig as base
  Merging arch/mips/configs/generic/32r2.config
  Merging arch/mips/configs/generic/el.config
  Merging ./arch/mips/configs/generic/board-boston.config
  Merging ./arch/mips/configs/generic/board-ni169445.config
  Merging ./arch/mips/configs/generic/board-ocelot.config
  Merging ./arch/mips/configs/generic/board-ranchu.config
  Merging ./arch/mips/configs/generic/board-sead-3.config
  Merging ./arch/mips/configs/generic/board-xilfpga.config
  #
  # configuration written to .config
  #
    SYNC    include/config/auto.conf
    CALL    scripts/checksyscalls.sh
    CALL    scripts/atomic/check-atomics.sh
    CHK     include/generated/compile.h
    CHK     include/generated/autoksyms.h

Reported-by: Elliot Berman <eberman@codeaurora.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-02 00:43:35 +09:00

5.2 KiB

SPDX-License-Identifier: GPL-2.0

Makefile for the linux kernel.

obj-y = fork.o exec_domain.o panic.o
cpu.o exit.o softirq.o resource.o
sysctl.o capability.o ptrace.o user.o
signal.o sys.o umh.o workqueue.o pid.o task_work.o
extable.o params.o
kthread.o sys_ni.o nsproxy.o
notifier.o ksysfs.o cred.o reboot.o
async.o range.o smpboot.o ucount.o regset.o

obj-$(CONFIG_USERMODE_DRIVER) += usermode_driver.o obj-$(CONFIG_MODULES) += kmod.o obj-$(CONFIG_MULTIUSER) += groups.o

ifdef CONFIG_FUNCTION_TRACER

Do not trace internal ftrace files

CFLAGS_REMOVE_irq_work.o = $(CC_FLAGS_FTRACE) endif

Prevents flicker of uninteresting __do_softirq()/__local_bh_disable_ip()

in coverage traces.

KCOV_INSTRUMENT_softirq.o := n

Avoid KCSAN instrumentation in softirq ("No shared variables, all the data

are CPU local" => assume no data races), to reduce overhead in interrupts.

KCSAN_SANITIZE_softirq.o = n

These are called from save_stack_trace() on slub debug path,

and produce insane amounts of uninteresting coverage.

KCOV_INSTRUMENT_module.o := n KCOV_INSTRUMENT_extable.o := n KCOV_INSTRUMENT_stacktrace.o := n

Don't self-instrument.

KCOV_INSTRUMENT_kcov.o := n

If sanitizers detect any issues in kcov, it may lead to recursion

via printk, etc.

KASAN_SANITIZE_kcov.o := n KCSAN_SANITIZE_kcov.o := n UBSAN_SANITIZE_kcov.o := n CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector

Don't instrument error handlers

CFLAGS_REMOVE_cfi.o := $(CC_FLAGS_CFI)

obj-y += sched/ obj-y += locking/ obj-y += power/ obj-y += printk/ obj-y += irq/ obj-y += rcu/ obj-y += livepatch/ obj-y += dma/ obj-y += entry/

obj-$(CONFIG_KCMP) += kcmp.o obj-$(CONFIG_FREEZER) += freezer.o obj-$(CONFIG_PROFILING) += profile.o obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-y += time/ obj-$(CONFIG_FUTEX) += futex.o obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o obj-$(CONFIG_SMP) += smp.o ifneq ($(CONFIG_SMP),y) obj-y += up.o endif obj-$(CONFIG_UID16) += uid16.o obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_MODULE_SIG) += module_signing.o obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signature.o obj-$(CONFIG_KALLSYMS) += kallsyms.o obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o obj-$(CONFIG_CRASH_CORE) += crash_core.o obj-$(CONFIG_KEXEC_CORE) += kexec_core.o obj-$(CONFIG_KEXEC) += kexec.o obj-$(CONFIG_KEXEC_FILE) += kexec_file.o obj-$(CONFIG_KEXEC_ELF) += kexec_elf.o obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o obj-$(CONFIG_COMPAT) += compat.o obj-$(CONFIG_CGROUPS) += cgroup/ obj-$(CONFIG_UTS_NS) += utsname.o obj-$(CONFIG_USER_NS) += user_namespace.o obj-$(CONFIG_PID_NS) += pid_namespace.o obj-$(CONFIG_IKCONFIG) += configs.o obj-$(CONFIG_IKHEADERS) += kheaders.o obj-$(CONFIG_SMP) += stop_machine.o obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o obj-$(CONFIG_AUDIT) += audit.o auditfilter.o obj-$(CONFIG_AUDITSYSCALL) += auditsc.o audit_watch.o audit_fsnotify.o audit_tree.o obj-$(CONFIG_GCOV_KERNEL) += gcov/ obj-$(CONFIG_KCOV) += kcov.o obj-$(CONFIG_KPROBES) += kprobes.o obj-$(CONFIG_FAIL_FUNCTION) += fail_function.o obj-$(CONFIG_KGDB) += debug/ obj-$(CONFIG_DETECT_HUNG_TASK) += hung_task.o obj-$(CONFIG_LOCKUP_DETECTOR) += watchdog.o obj-$(CONFIG_HARDLOCKUP_DETECTOR_PERF) += watchdog_hld.o obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RELAY) += relay.o obj-$(CONFIG_SYSCTL) += utsname_sysctl.o obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o obj-$(CONFIG_TRACEPOINTS) += tracepoint.o obj-$(CONFIG_LATENCYTOP) += latencytop.o obj-$(CONFIG_FUNCTION_TRACER) += trace/ obj-$(CONFIG_TRACING) += trace/ obj-$(CONFIG_TRACE_CLOCK) += trace/ obj-$(CONFIG_RING_BUFFER) += trace/ obj-$(CONFIG_TRACEPOINTS) += trace/ obj-$(CONFIG_IRQ_WORK) += irq_work.o obj-$(CONFIG_CPU_PM) += cpu_pm.o obj-$(CONFIG_BPF) += bpf/ obj-$(CONFIG_KCSAN) += kcsan/ obj-$(CONFIG_SHADOW_CALL_STACK) += scs.o obj-$(CONFIG_HAVE_STATIC_CALL_INLINE) += static_call.o obj-$(CONFIG_CFI_CLANG) += cfi.o

obj-$(CONFIG_PERF_EVENTS) += events/

obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o obj-$(CONFIG_PADATA) += padata.o obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o obj-$(CONFIG_TORTURE_TEST) += torture.o

obj-$(CONFIG_HAS_IOMEM) += iomem.o obj-$(CONFIG_RSEQ) += rseq.o obj-$(CONFIG_WATCH_QUEUE) += watch_queue.o

obj-$(CONFIG_RESOURCE_KUNIT_TEST) += resource_kunit.o obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o

CFLAGS_stackleak.o += $(DISABLE_STACKLEAK_PLUGIN) obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o KASAN_SANITIZE_stackleak.o := n KCSAN_SANITIZE_stackleak.o := n KCOV_INSTRUMENT_stackleak.o := n

obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o

$(obj)/configs.o: $(obj)/config_data.gz

targets += config_data config_data.gz $(obj)/config_data.gz: $(obj)/config_data FORCE $(call if_changed,gzip)

filechk_cat = cat $<

$(obj)/config_data: $(KCONFIG_CONFIG) FORCE $(call filechk,cat)

$(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz

quiet_cmd_genikh = CHK $(obj)/kheaders_data.tar.xz cmd_genikh = $(CONFIG_SHELL) $(srctree)/kernel/gen_kheaders.sh $@ $(obj)/kheaders_data.tar.xz: FORCE $(call cmd,genikh)

clean-files := kheaders_data.tar.xz kheaders.md5