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a69fe1a2c9
linux-next has been reporting gazillion warnings for ARC build and I finally decided to take a bite: http://kisskb.ellerman.id.au/kisskb/buildresult/12638735/ Most of the them are due to -Wmaybe-uninitialized | ../kernel/sysctl.c: In function '__do_proc_doulongvec_minmax': | ../kernel/sysctl.c:1928:12: warning: 'p' may be used uninitialized in this function [-Wmaybe-uninitialized] | ret = tmp - *buf; | ^ | ../kernel/sysctl.c:2342:29: note: 'p' was declared here | char *kbuf = NULL, *p; | ^ | ... | ... Cursory look at code seemed fine and a definite gcc false positive in say kernel/sysctl.c Mystery was why only for ARC (and not with ARM linaro toolchain based off same gcc 4.8). Turns out that -O3 (default for ARC) triggers these and if I enable -O3 for ARM kernel build, I see the same splat. I initially wanted to disable this only for gcc 4.8, but Arnd reported it is seen even on gcc 6.0 for ARM with -O3. Thus better to disable this independent of gcc version. Cc: Claudiu Zissulescu <Claudiu.Zissulescu@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Michal Marek <mmarek@suse.cz> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
156 lines
4.4 KiB
Makefile
156 lines
4.4 KiB
Makefile
#
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# Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License version 2 as
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# published by the Free Software Foundation.
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#
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UTS_MACHINE := arc
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ifeq ($(CROSS_COMPILE),)
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ifndef CONFIG_CPU_BIG_ENDIAN
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CROSS_COMPILE := arc-linux-
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else
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CROSS_COMPILE := arceb-linux-
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endif
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endif
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KBUILD_DEFCONFIG := nsim_700_defconfig
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cflags-y += -fno-common -pipe -fno-builtin -D__linux__
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cflags-$(CONFIG_ISA_ARCOMPACT) += -mA7
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cflags-$(CONFIG_ISA_ARCV2) += -mcpu=archs
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is_700 = $(shell $(CC) -dM -E - < /dev/null | grep -q "ARC700" && echo 1 || echo 0)
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ifdef CONFIG_ISA_ARCOMPACT
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ifeq ($(is_700), 0)
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$(error Toolchain not configured for ARCompact builds)
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endif
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endif
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ifdef CONFIG_ISA_ARCV2
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ifeq ($(is_700), 1)
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$(error Toolchain not configured for ARCv2 builds)
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endif
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endif
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ifdef CONFIG_ARC_CURR_IN_REG
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# For a global register defintion, make sure it gets passed to every file
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# We had a customer reported bug where some code built in kernel was NOT using
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# any kernel headers, and missing the r25 global register
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# Can't do unconditionally because of recursive include issues
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# due to <linux/thread_info.h>
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LINUXINCLUDE += -include ${src}/arch/arc/include/asm/current.h
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endif
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upto_gcc44 := $(call cc-ifversion, -le, 0404, y)
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atleast_gcc44 := $(call cc-ifversion, -ge, 0404, y)
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atleast_gcc48 := $(call cc-ifversion, -ge, 0408, y)
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cflags-$(atleast_gcc44) += -fsection-anchors
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cflags-$(CONFIG_ARC_HAS_LLSC) += -mlock
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cflags-$(CONFIG_ARC_HAS_SWAPE) += -mswape
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ifdef CONFIG_ISA_ARCV2
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ifndef CONFIG_ARC_HAS_LL64
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cflags-y += -mno-ll64
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endif
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ifndef CONFIG_ARC_HAS_DIV_REM
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cflags-y += -mno-div-rem
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endif
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endif
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cflags-$(CONFIG_ARC_DW2_UNWIND) += -fasynchronous-unwind-tables
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# By default gcc 4.8 generates dwarf4 which kernel unwinder can't grok
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ifeq ($(atleast_gcc48),y)
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cflags-$(CONFIG_ARC_DW2_UNWIND) += -gdwarf-2
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endif
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ifndef CONFIG_CC_OPTIMIZE_FOR_SIZE
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# Generic build system uses -O2, we want -O3
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# Note: No need to add to cflags-y as that happens anyways
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#
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# Disable the false maybe-uninitialized warings gcc spits out at -O3
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ARCH_CFLAGS += -O3 $(call cc-disable-warning,maybe-uninitialized,)
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endif
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# small data is default for elf32 tool-chain. If not usable, disable it
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# This also allows repurposing GP as scratch reg to gcc reg allocator
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disable_small_data := y
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cflags-$(disable_small_data) += -mno-sdata -fcall-used-gp
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cflags-$(CONFIG_CPU_BIG_ENDIAN) += -mbig-endian
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ldflags-$(CONFIG_CPU_BIG_ENDIAN) += -EB
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# STAR 9000518362: (fixed with binutils shipping with gcc 4.8)
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# arc-linux-uclibc-ld (buildroot) or arceb-elf32-ld (EZChip) don't accept
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# --build-id w/o "-marclinux". Default arc-elf32-ld is OK
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ldflags-$(upto_gcc44) += -marclinux
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LIBGCC := $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
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# Modules with short calls might break for calls into builtin-kernel
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KBUILD_CFLAGS_MODULE += -mlong-calls -mno-millicode
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# Finally dump eveything into kernel build system
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KBUILD_CFLAGS += $(cflags-y)
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KBUILD_AFLAGS += $(KBUILD_CFLAGS)
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LDFLAGS += $(ldflags-y)
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head-y := arch/arc/kernel/head.o
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# See arch/arc/Kbuild for content of core part of the kernel
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core-y += arch/arc/
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# w/o this dtb won't embed into kernel binary
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core-y += arch/arc/boot/dts/
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core-$(CONFIG_ARC_PLAT_SIM) += arch/arc/plat-sim/
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core-$(CONFIG_ARC_PLAT_TB10X) += arch/arc/plat-tb10x/
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core-$(CONFIG_ARC_PLAT_AXS10X) += arch/arc/plat-axs10x/
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drivers-$(CONFIG_OPROFILE) += arch/arc/oprofile/
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libs-y += arch/arc/lib/ $(LIBGCC)
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boot := arch/arc/boot
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#default target for make without any arguements.
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KBUILD_IMAGE := bootpImage
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all: $(KBUILD_IMAGE)
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bootpImage: vmlinux
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boot_targets += uImage uImage.bin uImage.gz
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$(boot_targets): vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
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%.dtb %.dtb.S %.dtb.o: scripts
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$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
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dtbs: scripts
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$(Q)$(MAKE) $(build)=$(boot)/dts
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archclean:
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$(Q)$(MAKE) $(clean)=$(boot)
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# Hacks to enable final link due to absence of link-time branch relexation
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# and gcc choosing optimal(shorter) branches at -O3
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#
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# vineetg Feb 2010: -mlong-calls switched off for overall kernel build
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# However lib/decompress_inflate.o (.init.text) calls
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# zlib_inflate_workspacesize (.text) causing relocation errors.
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# Thus forcing all exten calls in this file to be long calls
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export CFLAGS_decompress_inflate.o = -mmedium-calls
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export CFLAGS_initramfs.o = -mmedium-calls
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ifdef CONFIG_SMP
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export CFLAGS_core.o = -mmedium-calls
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endif
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