LXR busybox/Makefile.flags

   1# ==========================================================================
   2# Build system
   3# ==========================================================================
   4
   5BB_VER = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
   6export BB_VER
   7SKIP_STRIP ?= n
   8
   9# -std=gnu99 needed for [U]LLONG_MAX on some systems
  10CPPFLAGS += $(call cc-option,-std=gnu99,)
  11
  12CPPFLAGS += \
  13        -Iinclude -Ilibbb \
  14        $(if $(KBUILD_SRC),-Iinclude2 -I$(srctree)/include -I$(srctree)/libbb) \
  15        -include include/autoconf.h \
  16        -D_GNU_SOURCE -DNDEBUG \
  17        $(if $(CONFIG_LFS),-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64) \
  18        $(if $(CONFIG_TIME64),-D_TIME_BITS=64) \
  19        -DBB_VER=$(squote)$(quote)$(BB_VER)$(quote)$(squote)
  20
  21CFLAGS += $(call cc-option,-Wall,)
  22CFLAGS += $(call cc-option,-Wshadow,)
  23CFLAGS += $(call cc-option,-Wwrite-strings,)
  24CFLAGS += $(call cc-option,-Wundef,)
  25CFLAGS += $(call cc-option,-Wstrict-prototypes,)
  26CFLAGS += $(call cc-option,-Wunused -Wunused-parameter,)
  27CFLAGS += $(call cc-option,-Wunused-function -Wunused-value,)
  28CFLAGS += $(call cc-option,-Wmissing-prototypes -Wmissing-declarations,)
  29CFLAGS += $(call cc-option,-Wno-format-security,)
  30# warn about C99 declaration after statement
  31CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
  32# If you want to add more -Wsomething above, make sure that it is
  33# still possible to build bbox without warnings.
  34
  35ifeq ($(CONFIG_WERROR),y)
  36CFLAGS += $(call cc-option,-Werror,)
  37## TODO:
  38## gcc version 4.4.0 20090506 (Red Hat 4.4.0-4) (GCC) is a PITA:
  39## const char *ptr; ... off_t v = *(off_t*)ptr; -> BOOM
  40## and no easy way to convince it to shut the hell up.
  41## We have a lot of such things all over the place.
  42## Classic *(off_t*)(void*)ptr does not work,
  43## and I am unwilling to do crazy gcc specific ({ void *ppp = ...; })
  44## stuff in macros. This would obfuscate the code too much.
  45## Maybe try __attribute__((__may_alias__))?
  46#CFLAGS += $(call cc-ifversion, -eq, 0404, -fno-strict-aliasing)
  47endif
  48# gcc 3.x emits bogus "old style proto" warning on find.c:alloc_action()
  49CFLAGS += $(call cc-ifversion, -ge, 0400, -Wold-style-definition)
  50
  51ifneq ($(lastword $(subst -, ,$(CC))),clang)
  52# "clang-9: warning: optimization flag '-finline-limit=0' is not supported
  53CFLAGS += $(call cc-option,-finline-limit=0,)
  54endif
  55
  56CFLAGS += $(call cc-option,-fno-builtin-strlen -fomit-frame-pointer -ffunction-sections -fdata-sections,)
  57# -fno-guess-branch-probability: prohibit pseudo-random guessing
  58# of branch probabilities (hopefully makes bloatcheck more stable):
  59CFLAGS += $(call cc-option,-fno-guess-branch-probability,)
  60CFLAGS += $(call cc-option,-funsigned-char,)
  61
  62ifeq ($(CONFIG_STATIC_LIBGCC),y)
  63# Disable it, for example, if you get
  64# "clang-9: warning: argument unused during compilation: '-static-libgcc'"
  65CFLAGS += $(call cc-option,-static-libgcc,)
  66endif
  67
  68CFLAGS += $(call cc-option,-falign-functions=1,)
  69ifneq ($(lastword $(subst -, ,$(CC))),clang)
  70# "clang-9: warning: optimization flag '-falign-jumps=1' is not supported" (and same for other two)
  71CFLAGS += $(call cc-option,-falign-jumps=1 -falign-labels=1 -falign-loops=1,)
  72endif
  73
  74# Defeat .eh_frame bloat (gcc 4.6.3 x86-32 defconfig: 20% smaller busybox binary):
  75CFLAGS += $(call cc-option,-fno-unwind-tables,)
  76CFLAGS += $(call cc-option,-fno-asynchronous-unwind-tables,)
  77# No automatic printf->puts,putchar conversions
  78# (try disabling this and comparing assembly, it's instructive)
  79CFLAGS += $(call cc-option,-fno-builtin-printf,)
  80
  81# clang-9 does not like "str" + N and "if (CONFIG_ITEM && cond)" constructs
  82ifeq ($(lastword $(subst -, ,$(CC))),clang)
  83CFLAGS += $(call cc-option,-Wno-string-plus-int -Wno-constant-logical-operand)
  84endif
  85
  86# FIXME: These warnings are at least partially to be concerned about and should
  87# be fixed..
  88#CFLAGS += $(call cc-option,-Wconversion,)
  89
  90ifneq ($(CONFIG_DEBUG),y)
  91CFLAGS += $(call cc-option,-Oz,$(call cc-option,-Os,$(call cc-option,-O2,)))
  92else
  93CFLAGS += $(call cc-option,-g,)
  94#CFLAGS += "-D_FORTIFY_SOURCE=2"
  95ifeq ($(CONFIG_DEBUG_PESSIMIZE),y)
  96CFLAGS += $(call cc-option,-O0,)
  97else
  98CFLAGS += $(call cc-option,-Oz,$(call cc-option,-Os,$(call cc-option,-O2,)))
  99endif
 100endif
 101ifeq ($(CONFIG_DEBUG_SANITIZE),y)
 102CFLAGS += $(call cc-option,-fsanitize=address,)
 103CFLAGS += $(call cc-option,-fsanitize=leak,)
 104CFLAGS += $(call cc-option,-fsanitize=undefined,)
 105endif
 106
 107# If arch/$(ARCH)/Makefile did not override it (with, say, -fPIC)...
 108ARCH_FPIC ?= -fpic
 109ARCH_FPIE ?= -fpie
 110ARCH_PIE ?= -pie
 111
 112# Usage: $(eval $(call pkg_check_modules,VARIABLE-PREFIX,MODULES))
 113define pkg_check_modules
 114$(1)_CFLAGS := $(shell $(PKG_CONFIG) $(PKG_CONFIG_FLAGS) --cflags $(2))
 115$(1)_LIBS := $(shell $(PKG_CONFIG) $(PKG_CONFIG_FLAGS) --libs $(2))
 116endef
 117
 118ifeq ($(CONFIG_BUILD_LIBBUSYBOX),y)
 119# on i386: 14% smaller libbusybox.so
 120# (code itself is 9% bigger, we save on relocs/PLT/GOT)
 121CFLAGS += $(ARCH_FPIC)
 122# and another 4% reduction of libbusybox.so:
 123# (external entry points must be marked EXTERNALLY_VISIBLE)
 124CFLAGS += $(call cc-option,-fvisibility=hidden)
 125endif
 126
 127ifeq ($(CONFIG_STATIC),y)
 128CFLAGS_busybox += -static
 129PKG_CONFIG_FLAGS += --static
 130endif
 131
 132ifeq ($(CONFIG_PIE),y)
 133CFLAGS_busybox += $(ARCH_PIE)
 134CFLAGS += $(ARCH_FPIE)
 135endif
 136
 137ifneq ($(CONFIG_EXTRA_CFLAGS),)
 138CFLAGS += $(strip $(subst ",,$(CONFIG_EXTRA_CFLAGS)))
 139#"))
 140endif
 141
 142# Note: both "" (string consisting of two quote chars) and empty string
 143# are possible, and should be skipped below.
 144ifneq ($(subst "",,$(CONFIG_SYSROOT)),)
 145CFLAGS += --sysroot=$(CONFIG_SYSROOT)
 146export SYSROOT=$(CONFIG_SYSROOT)
 147endif
 148
 149# libm may be needed for dc, awk, ntpd
 150LDLIBS += m
 151# Android has no separate crypt library
 152# gcc-4.2.1 fails if we try to feed C source on stdin:
 153#  echo 'int main(void){return 0;}' | $(CC) $(CFLAGS) -lcrypt -o /dev/null -xc -
 154# fall back to using a temp file:
 155CRYPT_AVAILABLE := $(shell echo 'int main(void){return 0;}' >bb_libtest.c; $(CC) $(CFLAGS) $(CFLAGS_busybox) -lcrypt -o /dev/null bb_libtest.c >/dev/null 2>&1 && echo "y"; rm bb_libtest.c)
 156RT_AVAILABLE    := $(shell echo 'int main(void){return 0;}' >bb_libtest.c; $(CC) $(CFLAGS) $(CFLAGS_busybox) -lrt    -o /dev/null bb_libtest.c >/dev/null 2>&1 && echo "y"; rm bb_libtest.c)
 157ifeq ($(CRYPT_AVAILABLE),y)
 158LDLIBS += crypt
 159endif
 160# librt may be needed for clock_gettime()
 161ifeq ($(RT_AVAILABLE),y)
 162LDLIBS += rt
 163endif
 164
 165# libpam may use libpthread, libdl and/or libaudit.
 166# On some platforms that requires an explicit -lpthread, -ldl, -laudit.
 167# However, on *other platforms* it fails when some of those flags
 168# given needlessly. On some systems, crypt needs pthread.
 169#
 170# I even had a system where a runtime test for pthread
 171# (similar to CRYPT_AVAILABLE test above) was not reliable.
 172#
 173# Do not propagate this mess by adding libraries to CONFIG_PAM/CRYPT_AVAILABLE blocks.
 174# Add libraries you need to CONFIG_EXTRA_LDLIBS instead.
 175
 176ifeq ($(CONFIG_PAM),y)
 177LDLIBS += pam pam_misc
 178endif
 179
 180ifeq ($(CONFIG_SELINUX),y)
 181SELINUX_PC_MODULES = libselinux libsepol
 182$(eval $(call pkg_check_modules,SELINUX,$(SELINUX_PC_MODULES)))
 183CPPFLAGS += $(SELINUX_CFLAGS)
 184LDLIBS += $(if $(SELINUX_LIBS),$(SELINUX_LIBS:-l%=%),$(SELINUX_PC_MODULES:lib%=%))
 185endif
 186
 187ifeq ($(CONFIG_FEATURE_NSLOOKUP_BIG),y)
 188ifneq (,$(findstring linux,$(shell $(CC) $(CFLAGS) -dumpmachine)))
 189LDLIBS += resolv
 190endif
 191ifneq (,$(findstring gnu,$(shell $(CC) $(CFLAGS) -dumpmachine)))
 192LDLIBS += resolv
 193endif
 194endif
 195
 196ifeq ($(CONFIG_EFENCE),y)
 197LDLIBS += efence
 198endif
 199
 200ifeq ($(CONFIG_DMALLOC),y)
 201LDLIBS += dmalloc
 202endif
 203
 204# If a flat binary should be built, CFLAGS_busybox="-elf2flt"
 205# env var should be set for make invocation.
 206# Here we check whether CFLAGS_busybox indeed contains that flag.
 207# (For historical reasons, we also check LDFLAGS, which doesn't
 208# seem to be entirely correct variable to put "-elf2flt" into).
 209W_ELF2FLT = -elf2flt
 210ifneq (,$(findstring $(W_ELF2FLT),$(LDFLAGS) $(CFLAGS_busybox)))
 211SKIP_STRIP = y
 212endif
 213
 214ifneq ($(CONFIG_EXTRA_LDFLAGS),)
 215LDFLAGS += $(strip $(subst ",,$(CONFIG_EXTRA_LDFLAGS)))
 216#"))
 217endif
 218
 219# Busybox is a stack-fatty so make sure we increase default size
 220# TODO: use "make stksizes" to find & fix big stack users
 221# (we stole scripts/checkstack.pl from the kernel... thanks guys!)
 222# Reduced from 20k to 16k in 1.9.0.
 223FLTFLAGS += -s 16000
 224