Currently a number of Makefiles break when used with toolchains that
pass extra flags in CC and other cross-compile related variables (such
as --sysroot).
Thus we get this error when we use a toolchain that puts --sysroot in
the CC var:
~/src/linux/tools$ make iio
[snip]
iio_event_monitor.c:18:10: fatal error: unistd.h: No such file or directory
#include <unistd.h>
^~~~~~~~~~
This occurs because we clobber several env vars related to
cross-compiling with lines like this:
CC = $(CROSS_COMPILE)gcc
Although this will point to a valid cross-compiler, we lose any extra
flags that might exist in the CC variable, which can break toolchains
that rely on them (for example, those that use --sysroot).
This easily shows up using a Yocto SDK:
$ . [snip]/sdk/environment-setup-cortexa8hf-neon-poky-linux-gnueabi
$ echo $CC
arm-poky-linux-gnueabi-gcc -march=armv7-a -mfpu=neon -mfloat-abi=hard
-mcpu=cortex-a8
--sysroot=[snip]/sdk/sysroots/cortexa8hf-neon-poky-linux-gnueabi
$ echo $CROSS_COMPILE
arm-poky-linux-gnueabi-
$ echo ${CROSS_COMPILE}gcc
krm-poky-linux-gnueabi-gcc
Although arm-poky-linux-gnueabi-gcc is a cross-compiler, we've lost the
--sysroot and other flags that enable us to find the right libraries to
link against, so we can't find unistd.h and other libraries and headers.
Normally with the --sysroot flag we would find unistd.h in the sdk
directory in the sysroot:
$ find [snip]/sdk/sysroots -path '*/usr/include/unistd.h'
[snip]/sdk/sysroots/cortexa8hf-neon-poky-linux-gnueabi/usr/include/unistd.h
The perf Makefile adds CC = $(CROSS_COMPILE)gcc if and only if CC is not
already set, and it compiles correctly with the above toolchain.
So, generalize the logic that perf uses in the common Makefile and
remove the manual CC = $(CROSS_COMPILE)gcc lines from each Makefile.
Note that this patch does not fix cross-compile for all the tools (some
have other bugs), but it does fix it for all except usb and acpi, which
still have other unrelated issues.
I tested both with and without the patch on native and cross-build and
there appear to be no regressions.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Martin Kelly <[email protected]>
Acked-by: Mark Brown <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Stephen Hemminger <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Pali Rohar <[email protected]>
Cc: Richard Purdie <[email protected]>
Cc: Jacek Anaszewski <[email protected]>
Cc: Pavel Machek <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Robert Moore <[email protected]>
Cc: Lv Zheng <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Valentina Manea <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Mario Limonciello <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
# SPDX-License-Identifier: GPL-2.0
# Makefile for cgroup tools
-CC = $(CROSS_COMPILE)gcc
CFLAGS = -Wall -Wextra
all: cgroup_event_listener
# (this improves performance and avoids hard-to-debug behaviour);
MAKEFLAGS += -r
-CC = $(CROSS_COMPILE)gcc
-LD = $(CROSS_COMPILE)ld
CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
ALL_TARGETS := lsgpio gpio-hammer gpio-event-mon
# SPDX-License-Identifier: GPL-2.0
# Makefile for Hyper-V tools
-CC = $(CROSS_COMPILE)gcc
WARNINGS = -Wall -Wextra
CFLAGS = $(WARNINGS) -g $(shell getconf LFS_CFLAGS)
# (this improves performance and avoids hard-to-debug behaviour);
MAKEFLAGS += -r
-CC = $(CROSS_COMPILE)gcc
-LD = $(CROSS_COMPILE)ld
CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
ALL_TARGETS := iio_event_monitor lsiio iio_generic_buffer
PREFIX ?= /usr
SBINDIR ?= sbin
INSTALL ?= install
-CC = $(CROSS_COMPILE)gcc
TARGET = freefall
# SPDX-License-Identifier: GPL-2.0
# Makefile for LEDs tools
-CC = $(CROSS_COMPILE)gcc
CFLAGS = -Wall -Wextra -g -I../../include/uapi
all: uledmon led_hw_brightness_mon
$(eval $(1) = $(2)))
endef
-# Allow setting CC and AR and LD, or setting CROSS_COMPILE as a prefix.
-$(call allow-override,CC,$(CROSS_COMPILE)gcc)
-$(call allow-override,AR,$(CROSS_COMPILE)ar)
-$(call allow-override,LD,$(CROSS_COMPILE)ld)
-$(call allow-override,CXX,$(CROSS_COMPILE)g++)
-
LD += $(EXTRA_LDFLAGS)
HOSTCC ?= gcc
# to compile vs uClibc, that can be done here as well.
CROSS = #/usr/i386-linux-uclibc/usr/bin/i386-uclibc-
CROSS_COMPILE ?= $(CROSS)
-CC = $(CROSS_COMPILE)gcc
-LD = $(CROSS_COMPILE)gcc
-STRIP = $(CROSS_COMPILE)strip
HOSTCC = gcc
# check if compiler option is supported
CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
+# Makefiles suck: This macro sets a default value of $(2) for the
+# variable named by $(1), unless the variable has been set by
+# environment or command line. This is necessary for CC and AR
+# because make sets default values, so the simpler ?= approach
+# won't work as expected.
+define allow-override
+ $(if $(or $(findstring environment,$(origin $(1))),\
+ $(findstring command line,$(origin $(1)))),,\
+ $(eval $(1) = $(2)))
+endef
+
+# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
+$(call allow-override,CC,$(CROSS_COMPILE)gcc)
+$(call allow-override,AR,$(CROSS_COMPILE)ar)
+$(call allow-override,LD,$(CROSS_COMPILE)ld)
+$(call allow-override,CXX,$(CROSS_COMPILE)g++)
+$(call allow-override,STRIP,$(CROSS_COMPILE)strip)
+
ifeq ($(CC_NO_CLANG), 1)
EXTRA_WARNINGS += -Wstrict-aliasing=3
endif
# (this improves performance and avoids hard-to-debug behaviour);
MAKEFLAGS += -r
-CC = $(CROSS_COMPILE)gcc
-LD = $(CROSS_COMPILE)ld
CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
ALL_TARGETS := spidev_test spidev_fdx
# SPDX-License-Identifier: GPL-2.0
# Makefile for USB tools
-CC = $(CROSS_COMPILE)gcc
PTHREAD_LIBS = -lpthread
WARNINGS = -Wall -Wextra
CFLAGS = $(WARNINGS) -g -I../include
LIB_DIR = ../lib/api
LIBS = $(LIB_DIR)/libapi.a
-CC = $(CROSS_COMPILE)gcc
CFLAGS = -Wall -Wextra -I../lib/
LDFLAGS = $(LIBS)
SBINDIR ?= sbin
INSTALL ?= install
CFLAGS += -D__EXPORTED_HEADERS__ -I../../include/uapi -I../../include
-CC = $(CROSS_COMPILE)gcc
TARGET = dell-smbios-example
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