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