linux-yocto/arch/um/Makefile
Masahiro Yamada 8f55d71b57 um: let 'make clean' properly clean underlying SUBARCH as well
[ Upstream commit ab09da7570 ]

Building the kernel with O= is affected by stale in-tree build artifacts.

So, if the source tree is not clean, Kbuild displays the following:

  $ make ARCH=um O=build defconfig
  make[1]: Entering directory '/.../linux/build'
  ***
  *** The source tree is not clean, please run 'make ARCH=um mrproper'
  *** in /.../linux
  ***
  make[2]: *** [/.../linux/Makefile:673: outputmakefile] Error 1
  make[1]: *** [/.../linux/Makefile:248: __sub-make] Error 2
  make[1]: Leaving directory '/.../linux/build'
  make: *** [Makefile:248: __sub-make] Error 2

Usually, running 'make mrproper' is sufficient for cleaning the source
tree for out-of-tree builds.

However, building UML generates build artifacts not only in arch/um/,
but also in the SUBARCH directory (i.e., arch/x86/). If in-tree stale
files remain under arch/x86/, Kbuild will reuse them instead of creating
new ones under the specified build directory.

This commit makes 'make ARCH=um clean' recurse into the SUBARCH directory.

Reported-by: Shuah Khan <skhan@linuxfoundation.org>
Closes: https://lore.kernel.org/lkml/20250502172459.14175-1-skhan@linuxfoundation.org/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-06-04 14:40:26 +02:00

5.1 KiB

This file is included by the global makefile so that you can add your own

architecture-specific flags and dependencies.

Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)

Licensed under the GPL

select defconfig based on actual architecture

ifeq ($(SUBARCH),x86) ifeq ($(shell uname -m),x86_64) KBUILD_DEFCONFIG := x86_64_defconfig else KBUILD_DEFCONFIG := i386_defconfig endif else KBUILD_DEFCONFIG := $(SUBARCH)_defconfig endif

ARCH_DIR := arch/um OS := $(shell uname -s)

We require bash because the vmlinux link and loader script cpp use bash

features.

SHELL := /bin/bash

core-y += $(ARCH_DIR)/kernel/
$(ARCH_DIR)/drivers/
$(ARCH_DIR)/os-$(OS)/

MODE_INCLUDE += -I$(srctree)/$(ARCH_DIR)/include/shared/skas

HEADER_ARCH := $(SUBARCH)

ifneq ($(filter $(SUBARCH),x86 x86_64 i386),) HEADER_ARCH := x86 endif

ifdef CONFIG_64BIT KBUILD_CFLAGS += -mcmodel=large endif

HOST_DIR := arch/$(HEADER_ARCH)

include $(srctree)/$(ARCH_DIR)/Makefile-skas include $(srctree)/$(HOST_DIR)/Makefile.um

core-y += $(HOST_DIR)/um/

SHARED_HEADERS := $(ARCH_DIR)/include/shared ARCH_INCLUDE := -I$(srctree)/$(SHARED_HEADERS) ARCH_INCLUDE += -I$(srctree)/$(HOST_DIR)/um/shared KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/um

-Dvmap=kernel_vmap prevents anything from referencing the libpcap.o symbol so

named - it's a common symbol in libpcap, so we get a binary which crashes.

Same things for in6addr_loopback and mktime - found in libc. For these two we

only get link-time error, luckily.

-Dlongjmp=kernel_longjmp prevents anything from referencing the libpthread.a

embedded copy of longjmp, same thing for setjmp.

These apply to USER_CFLAGS to.

KBUILD_CFLAGS += $(CFLAGS) $(CFLAGS-y) -D__arch_um__
$(ARCH_INCLUDE) $(MODE_INCLUDE) -Dvmap=kernel_vmap
-Dlongjmp=kernel_longjmp -Dsetjmp=kernel_setjmp
-Din6addr_loopback=kernel_in6addr_loopback
-Din6addr_any=kernel_in6addr_any -Dstrrchr=kernel_strrchr

KBUILD_AFLAGS += $(ARCH_INCLUDE)

USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS)))
$(ARCH_INCLUDE) $(MODE_INCLUDE) $(filter -I%,$(CFLAGS))
-D_FILE_OFFSET_BITS=64 -idirafter $(srctree)/include
-idirafter $(objtree)/include -D__KERNEL__ -D__UM_HOST__

#This will adjust *FLAGS accordingly to the platform. include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)

KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/include
-I$(srctree)/$(HOST_DIR)/include/uapi
-I$(objtree)/$(HOST_DIR)/include/generated
-I$(objtree)/$(HOST_DIR)/include/generated/uapi

-Derrno=kernel_errno - This turns all kernel references to errno into

kernel_errno to separate them from the libc errno. This allows -fno-common

in KBUILD_CFLAGS. Otherwise, it would cause ld to complain about the two different

errnos.

These apply to kernelspace only.

strip leading and trailing whitespace to make the USER_CFLAGS removal of these

defines more robust

KERNEL_DEFINES = $(strip -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask
-Dmktime=kernel_mktime $(ARCH_KERNEL_DEFINES)) KBUILD_CFLAGS += $(KERNEL_DEFINES)

PHONY += linux

all: linux

linux: vmlinux @echo ' LINK $@' $(Q)ln -f $< $@

define archhelp echo '* linux - Binary kernel image (./linux) - for backward' echo ' compatibility only, this creates a hard link to the' echo ' real kernel binary, the "vmlinux" binary you' echo ' find in the kernel root.' endef

archheaders: $(Q)$(MAKE) -f $(srctree)/Makefile ARCH=$(HEADER_ARCH) asm-generic archheaders

archprepare: $(Q)$(MAKE) $(build)=$(HOST_DIR)/um include/generated/user_constants.h

LINK-$(CONFIG_LD_SCRIPT_STATIC) += -static ifdef CONFIG_LD_SCRIPT_DYN LINK-$(call gcc-min-version, 60100)$(CONFIG_CC_IS_CLANG) += -no-pie endif LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib

CFLAGS_NO_HARDENING := $(call cc-option, -fno-PIC,) $(call cc-option, -fno-pic,)
-fno-stack-protector $(call cc-option, -fno-stack-protector-all)

Options used by linker script

export LDS_START := $(START) export LDS_ELF_ARCH := $(ELF_ARCH) export LDS_ELF_FORMAT := $(ELF_FORMAT)

The wrappers will select whether using "malloc" or the kernel allocator.

LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc

Avoid binutils 2.39+ warnings by marking the stack non-executable and

ignorning warnings for the kallsyms sections.

LDFLAGS_EXECSTACK = -z noexecstack ifeq ($(CONFIG_LD_IS_BFD),y) LDFLAGS_EXECSTACK += $(call ld-option,--no-warn-rwx-segments) endif

LD_FLAGS_CMDLINE = $(foreach opt,$(KBUILD_LDFLAGS),-Wl,$(opt))

Used by link-vmlinux.sh which has special support for um link

export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE) export LDFLAGS_vmlinux := $(LDFLAGS_EXECSTACK)

When cleaning we don't include .config, so we don't include

TT or skas makefiles and don't clean skas_ptregs.h.

CLEAN_FILES += linux x.i gmon.out MRPROPER_FILES += $(HOST_DIR)/include/generated

archclean: @find . ( -name '.bb' -o -name '.bbg' -o -name '.da'
-o -name '
.gcov' ) -type f -print | xargs rm -f $(Q)$(MAKE) -f $(srctree)/Makefile ARCH=$(HEADER_ARCH) clean

export HEADER_ARCH SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING OS DEV_NULL_PATH