forked from openkylin/platform_build
x86: Refine the way we configure the x86 build.
This is the result of a recent conversation around the x86 ABI and its relationship with how we build platform images. Briefly: - We want to use feature-based macros like ARCH_X86_HAVE_$FEATURE instead of relying on explicit compiler macros like -DUSE_$FEATURE - We want to allow for other x86-based arch variants, e.g. if someone wants to build Android for a CPU that doesn't support the NDK x86 ABI. However, we need to ensure these are not tagged compatible by mistake (see check at the end of TARGET_linux-x86.mk) - There are several flags which use is dubious now that we have a dedicated toolchain to build all the x86 stuff. Comment them as 'to be considered for removal'. We'll do the proper checks later. Change-Id: I7768d7c34d73e274cbf4c09ae831b55280d6bb58
This commit is contained in:
David 'Digit' Turner
parent
ec7a6448c6
commit
6371da10f8
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@ -22,6 +22,18 @@ ifeq ($(strip $(TARGET_ARCH_VARIANT)),)
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TARGET_ARCH_VARIANT := x86
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endif
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# Include the arch-variant-specific configuration file.
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# Its role is to define various ARCH_X86_HAVE_XXX feature macros,
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# plus initial values for TARGET_GLOBAL_CFLAGS
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#
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TARGET_ARCH_SPECIFIC_MAKEFILE := $(BUILD_COMBOS)/arch/$(TARGET_ARCH)/$(TARGET_ARCH_VARIANT).mk
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ifeq ($(strip $(wildcard $(TARGET_ARCH_SPECIFIC_MAKEFILE))),)
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$(error Unknown $(TARGET_ARCH) architecture version: $(TARGET_ARCH_VARIANT))
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endif
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include $(TARGET_ARCH_SPECIFIC_MAKEFILE)
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# You can set TARGET_TOOLS_PREFIX to get gcc from somewhere else
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ifeq ($(strip $(TARGET_TOOLS_PREFIX)),)
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TARGET_TOOLS_PREFIX := \
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@ -84,44 +96,48 @@ TARGET_GLOBAL_CFLAGS += \
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-funwind-tables \
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-include $(call select-android-config-h,target_linux-x86)
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# Needs to be fixed later
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#TARGET_GLOBAL_CFLAGS += \
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# -fstack-protector
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# Needs to be added for RELEASE
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#TARGET_GLOBAL_CFLAGS += \
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# -DNDEBUG
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# XXX: Not sure this is still needed. Must check with our toolchains.
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TARGET_GLOBAL_CPPFLAGS += \
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-fno-use-cxa-atexit
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ifeq ($(TARGET_ARCH_VARIANT),x86-atom)
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# Basic ATOM flags.
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TARGET_GLOBAL_CFLAGS += -march=atom -mstackrealign -mfpmath=sse
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# XXX: Our toolchain is normally configured to always set these flags by default
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# however, there have been reports that this is sometimes not the case. So make
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# them explicit here unless we have the time to carefully check it
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#
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TARGET_GLOBAL_CFLAGS += -mstackrealign -msse3 -mfpmath=sse
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# There are various levels of ATOM processors out there. Different ones have different
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# capabilities. This first define matches the NDK's minimum ABI requirements.
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# Note: Not all of the flags set here are actually used in Android. They are provided
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# to allow for the addition of corresponding optimizations.
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TARGET_GLOBAL_CFLAGS += -DUSE_MMX -DUSE_SSE -DUSE_SSE2 -DUSE_SSE3
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# If you wish to build a BSP that will only be used on hardware that has additional
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# available instructions, enable them here. By default, this is commented off so that
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# the default images can run on all processors that are NDK ABI compliant.
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# TARGET_GLOBAL_CFLAGS += -DUSE_SSSE3
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else
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# Plain 'x86' - lowest common denominator. This should run pretty much on any hardware.
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#
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# Note: The NDK's ABI (see the NDK ABI documentation) requires many of the more recent
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# instruction set additions. You can build an "x86" BSP that will run on very old hardware,
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# but it won't be able to run much of the x86 NDK compliant code.
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TARGET_GLOBAL_CFLAGS += -march=i686
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# XXX: These flags should not be defined here anymore. Instead, the Android.mk
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# of the modules that depend on these features should instead check the
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# corresponding macros (e.g. ARCH_X86_HAVE_SSE2 and ARCH_X86_HAVE_SSSE3)
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# Keep them here until this is all cleared up.
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#
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ifeq ($(ARCH_X86_HAVE_SSE2),true)
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TARGET_GLOBAL_CFLAGS += -DUSE_SSE2
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endif
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ifeq ($(ARCH_X86_HAVE_SSSE3),true) # yes, really SSSE3, not SSE3!
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TARGET_GLOBAL_CFLAGS += -DUSE_SSSE3
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endif
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# XXX: This flag is probably redundant. I believe our toolchain always sets
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# it by default. Consider for removal.
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#
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TARGET_GLOBAL_CFLAGS += -mbionic
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# XXX: This flag is probably redundant. The macro should be defined by our
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# toolchain binaries automatically (as a compiler built-in).
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# Check with: $BINPREFIX-gcc -dM -E < /dev/null
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#
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# Consider for removal.
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#
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TARGET_GLOBAL_CFLAGS += -D__ANDROID__
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# XXX: This flag is probably redundant since our toolchain binaries already
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# generate 32-bit machine code. It probably dates back to the old days
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# where we were using the host toolchain on Linux to build the platform
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# images. Consider it for removal.
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TARGET_GLOBAL_LDFLAGS += -m32
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TARGET_GLOBAL_LDFLAGS += -Wl,-z,noexecstack
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TARGET_GLOBAL_LDFLAGS += -Wl,--gc-sections
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@ -205,3 +221,21 @@ $(hide) $(PRIVATE_CXX) \
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-Wl,--end-group \
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$(if $(filter true,$(PRIVATE_NO_CRT)),,$(TARGET_CRTEND_O))
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endef
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# Special check for x86 NDK ABI compatibility.
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# The TARGET_CPU_ABI variable should be defined in BoardConfig.mk to 'x86'
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# *only* if the platform image is compatible with the NDK x86 ABI.
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#
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# We perform a small check here to ensure that nothing bad can happen.
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#
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ifeq ($(TARGET_CPU_ABI),x86)
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ifneq (true-true-true-true,$(ARCH_X86_HAVE_MMX)-$(ARCH_X86_HAVE_SSE)-$(ARCH_X86_HAVE_SSE2)-$(ARCH_X86_HAVE_SSE3))
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$(info ERROR: Your x86 platform image is not compatible with the NDK x86 ABI)
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$(info As such, you should *not* define TARGET_CPU_ABI to 'x86' in your BoardConfig.mk)
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$(info to ensure that your device will not be mistakenly listed as compatible by
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$(info the Android Market. Also, it is likely that the image will fail the CTS tests)
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$(info Please undefine TARGET_CPU_ABI in your BoardConfig.mk, or select the value 'none')
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$(info The corresponding image will still be able to run Dalvik-based Android applications)
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$(error Aborting build! Please fix your BoardConfig.mk)
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endif
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endif
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@ -0,0 +1,18 @@
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# This file contains feature macro definitions specific to the
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# 'x86-atom' arch variant. This is an extension of the 'x86' base variant
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# that adds Atom-specific features.
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#
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# See build/core/combo/arch/x86/x86.mk for differences.
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#
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ARCH_X86_HAVE_MMX := true
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ARCH_X86_HAVE_SSE := true
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ARCH_X86_HAVE_SSE2 := true
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ARCH_X86_HAVE_SSE3 := true
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ARCH_X86_HAVE_SSSE3 := true
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ARCH_X86_HAVE_MOVBE := true
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ARCH_X86_HAVE_POPCNT := false # popcnt is not supported by current Atom CPUs
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# This flag is used to enabled Atom-specific optimizations with our toolchain
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#
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TARGET_GLOBAL_CFLAGS += -march=atom
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@ -0,0 +1,35 @@
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# This file contains feature macro definitions specific to the
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# base 'x86' platform ABI. This one must *strictly* match the NDK x86 ABI
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# which mandates specific CPU extensions to be available.
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#
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# It is also used to build full_x86-eng / sdk_x86-eng platform images that
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# are run in the emulator under KVM emulation (i.e. running directly on
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# the host development machine's CPU).
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#
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# If your target device doesn't support the four following features, then
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# it cannot be compatible with the NDK x86 ABI. You should define a new
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# target arch variant (e.g. "x86-mydevice") and a corresponding file
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# under build/core/combo/arch/x86/
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#
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ARCH_X86_HAVE_MMX := true
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ARCH_X86_HAVE_SSE := true
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ARCH_X86_HAVE_SSE2 := true
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ARCH_X86_HAVE_SSE3 := true
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# These features are optional and shall not be included in the base platform
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# Otherwise, they sdk_x86-eng system images might fail to run on some
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# developer machines.
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#
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ARCH_X86_HAVE_SSSE3 := false
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ARCH_X86_HAVE_MOVBE := false
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ARCH_X86_HAVE_POPCNT := false
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# XXX: This flag is probably redundant, because it should be set by default
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# by our toolchain binaries. However, there have been reports that this may
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# not always work as intended, so keep it unless we have the time to check
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# everything properly.
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TARGET_GLOBAL_CFLAGS += -march=i686
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