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Makefile: Use '=' instead of '?=' for make variables

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The '?=' will not assign value if the target make variable is
overriden via command-line or is set in environment variable.
On other hand, '=' will not assign value only if variable is
overriden via command-line parameter.

It is quite common to have CC, AS, CPP, LD, etc to be set as
environment variables pointing to native compiler and binutils.
If '-rR' option is not set in MAKEFLAGS then this results in
compile error because '?=' will use the native compiler and
binutils. If '-rR' option is set in MAKEFLAGS then this again
results in compile error because CC, AS, CPP, etc are set to
empty strings which causes '?=' to use empty string as compiler
and binutils.

To handle this, we use '?=' only when CROSS_COMPILE is not
defined and we use '=' when CROSS_COMPILE is defined.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
This commit is contained in:
Anup Patel
2019-01-04 08:45:36 +05:30
committed by Anup Patel
parent 45c9e14a2f
commit 2e5ede8279
1 changed files with 26 additions and 6 deletions
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32
Makefile
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@@ -100,7 +100,11 @@ GENFLAGS += $(platform-genflags-y)
GENFLAGS += $(firmware-genflags-y)
# Setup compilation environment
CC ?= $(CROSS_COMPILE)gcc
ifdef CROSS_COMPILE
CC = $(CROSS_COMPILE)gcc
else
CC ?= gcc
endif
CFLAGS = -g -Wall -Werror -nostdlib -fno-strict-aliasing -O2
CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
CFLAGS += -mno-save-restore -mstrict-align
@@ -108,12 +112,16 @@ CFLAGS += $(GENFLAGS)
CFLAGS += $(platform-cflags-y)
CFLAGS += $(firmware-cflags-y)
CPP ?= $(CROSS_COMPILE)cpp
ifdef CROSS_COMPILE
CPP = $(CROSS_COMPILE)cpp
else
CPP ?= cpp
endif
CPPFLAGS += $(GENFLAGS)
CPPFLAGS += $(platform-cppflags-y)
CPPFLAGS += $(firmware-cppflags-y)
AS = $(CC)
AS = $(CC)
ASFLAGS = -g -Wall -nostdlib -D__ASSEMBLY__
ASFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
ASFLAGS += -mno-save-restore -mstrict-align
@@ -121,17 +129,29 @@ ASFLAGS += $(GENFLAGS)
ASFLAGS += $(platform-asflags-y)
ASFLAGS += $(firmware-asflags-y)
AR ?= $(CROSS_COMPILE)ar
ifdef CROSS_COMPILE
AR = $(CROSS_COMPILE)ar
else
AR ?= ar
endif
ARFLAGS = rcs
LD ?= $(CROSS_COMPILE)ld
ifdef CROSS_COMPILE
LD = $(CROSS_COMPILE)ld
else
LD ?= ld
endif
LDFLAGS += -g -Wall -nostdlib -Wl,--build-id=none -N
LDFLAGS += $(platform-ldflags-y)
LDFLAGS += $(firmware-ldflags-y)
MERGEFLAGS += -r
OBJCOPY ?= $(CROSS_COMPILE)objcopy
ifdef CROSS_COMPILE
OBJCOPY = $(CROSS_COMPILE)objcopy
else
OBJCOPY ?= objcopy
endif
# Setup functions for compilation
define dynamic_flags