shell/README: describe special builtins

[oweals/busybox.git] / Makefile.flags

diff --git a/Makefile.flags b/Makefile.flags
index f27c601c83f8f0857346c07653e1288acdd08e18..60bb888d8db53d8dfdaaeee01abb4f3f500bd49c 100644 (file)
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -17,32 +17,36 @@ CPPFLAGS += \
        $(if $(CONFIG_LFS),-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64) \
        -D"BB_VER=KBUILD_STR($(BB_VER))" -DBB_BT=AUTOCONF_TIMESTAMP
 
-# flag checks are grouped together to speed the checks up a bit..
-CFLAGS += $(call cc-option,-Wall -Wshadow -Wwrite-strings,)
-CFLAGS += $(call cc-option,-Wundef -Wstrict-prototypes,)
+CFLAGS += $(call cc-option,-Wall,)
+CFLAGS += $(call cc-option,-Wshadow,)
+CFLAGS += $(call cc-option,-Wwrite-strings,)
+CFLAGS += $(call cc-option,-Wundef,)
+CFLAGS += $(call cc-option,-Wstrict-prototypes,)
 CFLAGS += $(call cc-option,-Wunused -Wunused-parameter,)
-# If you want to add "-Wmissing-prototypes -Wmissing-declarations" above
-# (or anything else for that matter) make sure that it is still possible
-# to build bbox without warnings. Current offender: find.c:alloc_action().
-# Looks more like gcc bug: gcc will warn on it with or without prototype.
-# But still, warning-free compile is a must, or else we will drown
-# in warnings pretty soon.
+CFLAGS += $(call cc-option,-Wunused-function -Wunused-value,)
+CFLAGS += $(call cc-option,-Wmissing-prototypes -Wmissing-declarations,)
+# warn about C99 declaration after statement
+CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
+# If you want to add more -Wsomething above, make sure that it is
+# still possible to build bbox without warnings.
 
 ifeq ($(CONFIG_WERROR),y)
 CFLAGS += $(call cc-option,-Werror,)
-else
-# for development, warn a little bit about unused results..
-CPPFLAGS += -D_FORTIFY_SOURCE=2
+## TODO:
+## gcc version 4.4.0 20090506 (Red Hat 4.4.0-4) (GCC) is a PITA:
+## const char *ptr; ... off_t v = *(off_t*)ptr; -> BOOM
+## and no easy way to convince it to shut the hell up.
+## We have a lot of such things all over the place.
+## Classic *(off_t*)(void*)ptr does not work,
+## and I am unwilling to do crazy gcc specific ({ void *ppp = ...; })
+## stuff in macros. This would obfuscate the code too much.
+## Maybe try __attribute__((__may_alias__))?
+#CFLAGS += $(call cc-ifversion, -eq, 0404, -fno-strict-aliasing)
 endif
 # gcc 3.x emits bogus "old style proto" warning on find.c:alloc_action()
 CFLAGS += $(call cc-ifversion, -ge, 0400, -Wold-style-definition)
 
-# gcc emits bogus "no prev proto" warning on find.c:alloc_action()
-ifneq ($(CONFIG_WERROR),y)
-CFLAGS += $(call cc-option,-Wmissing-prototypes -Wmissing-declarations,)
-endif
-
-CFLAGS += $(call cc-option,-Os -fno-builtin-strlen -finline-limit=0 -fomit-frame-pointer -ffunction-sections -fdata-sections,)
+CFLAGS += $(call cc-option,-fno-builtin-strlen -finline-limit=0 -fomit-frame-pointer -ffunction-sections -fdata-sections,)
 # -fno-guess-branch-probability: prohibit pseudo-random guessing
 # of branch probabilities (hopefully makes bloatcheck more stable):
 CFLAGS += $(call cc-option,-fno-guess-branch-probability,)
@@ -51,23 +55,46 @@ CFLAGS += $(call cc-option,-falign-functions=1 -falign-jumps=1 -falign-labels=1
 
 # FIXME: These warnings are at least partially to be concerned about and should
 # be fixed..
-#CFLAGS+=$(call cc-option,-Wconversion,)
+#CFLAGS += $(call cc-option,-Wconversion,)
 
-ifeq ($(CONFIG_DEBUG),y)
-CFLAGS += $(call cc-option,-g)
+ifneq ($(CONFIG_DEBUG),y)
+CFLAGS += $(call cc-option,-Os,)
+else
+CFLAGS += $(call cc-option,-g,)
+#CFLAGS += "-D_FORTIFY_SOURCE=2"
+ifeq ($(CONFIG_DEBUG_PESSIMIZE),y)
+CFLAGS += $(call cc-option,-O0,)
+else
+CFLAGS += $(call cc-option,-Os,)
 endif
+endif
+
+# If arch/$(ARCH)/Makefile did not override it (with, say, -fPIC)...
+ARCH_FPIC ?= -fpic
+ARCH_FPIE ?= -fpie
+ARCH_PIE ?= -pie
 
 ifeq ($(CONFIG_BUILD_LIBBUSYBOX),y)
 # on i386: 14% smaller libbusybox.so
 # (code itself is 9% bigger, we save on relocs/PLT/GOT)
-CFLAGS += -fpic
+CFLAGS += $(ARCH_FPIC)
 # and another 4% reduction of libbusybox.so:
 # (external entry points must be marked EXTERNALLY_VISIBLE)
 CFLAGS += $(call cc-option,-fvisibility=hidden)
 endif
 
 ifeq ($(CONFIG_STATIC),y)
-LDFLAGS += -static
+CFLAGS_busybox += -static
+endif
+
+ifeq ($(CONFIG_PIE),y)
+CFLAGS_busybox += $(ARCH_PIE)
+CFLAGS += $(ARCH_FPIE)
+endif
+
+ifneq ($(CONFIG_EXTRA_CFLAGS),)
+CFLAGS += $(strip $(subst ",,$(CONFIG_EXTRA_CFLAGS)))
+#"))
 endif
 
 LDLIBS += m crypt
@@ -88,10 +115,13 @@ ifeq ($(CONFIG_DMALLOC),y)
 LDLIBS += dmalloc
 endif
 
-#LDFLAGS += -nostdlib
-
-LDFLAGS_ELF2FLT = -Wl,-elf2flt
-ifneq (,$(findstring $(LDFLAGS_ELF2FLT),$(LDFLAGS)))
+# If a flat binary should be built, CFLAGS_busybox="-elf2flt"
+# env var should be set for make invocation.
+# Here we check whether CFLAGS_busybox indeed contains that flag.
+# (For historical reasons, we also check LDFLAGS, which doesn't
+# seem to be entirely correct variable to put "-elf2flt" into).
+W_ELF2FLT = -elf2flt
+ifneq (,$(findstring $(W_ELF2FLT),$(LDFLAGS) $(CFLAGS_busybox)))
 SKIP_STRIP = y
 endif