linux-kernel - Re: [PATCH] tools: fix cross-compile var export

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Message-ID: <20180107161140.GM6273@windriver.com>
Date:   Sun, 7 Jan 2018 11:11:41 -0500
From:   Paul Gortmaker <paul.gortmaker@...driver.com>
To:     Martin Kelly <martin@...tingkelly.com>
CC:     <kernel-kbuild@...r.kernel.org>, <kernel-janitors@...r.kernel.org>,
        <linux-embedded@...r.kernel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Matt Mackall <mpm@...enic.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tools: fix cross-compile var export

[[PATCH] tools: fix cross-compile var export] On 06/01/2018 (Sat 12:16) Martin Kelly wrote:

> From: Martin Kelly <martin@...tingkelly.com>
> 
> Currently in a number of Makefiles, we clobber the CC, LD, and/or STRIP env vars
> when cross-compiling, which breaks any additional flags that might be set (such
> as sysroot). This easily shows up by using, for instance, a Yocto SDK.
> 
> Fix this by more carefully overriding the flags in the way that the perf
> Makefile does.
> 
> This patch does not fix cross-compile for all the tools (some have other bugs),
> but it does appear to fix it for these:
> 
> - cgroup
> - freefall
> - gpio
> - hv
> - iio
> - leds
> - spi
> - vm
> - wmi
> 
> Signed-off-by: Martin Kelly <martin@...tingkelly.com>
> ---
> This patch touches multiple subsystems, and there doesn't appear to be a global
> tools maintainer, so I sent this to linux-embedded kernel-janitors, and
> linux-kbuild. Please let me know if there is a better place for it.

I think you will have better luck if you go subsystem by subsystem, e.g.
send gpio change to gpio maintainer, usb change to usb maintainer and so
on.  In addition, you'll want to try and understand/explain why those
lines were added in the 1st place and how it won't break other existing
use cases by removing them.  Maybe "git blame" will help for that...

P.
--

> 
>  tools/cgroup/Makefile            |  1 -
>  tools/gpio/Makefile              |  2 --
>  tools/hv/Makefile                |  1 -
>  tools/iio/Makefile               |  2 --
>  tools/laptop/freefall/Makefile   |  1 -
>  tools/leds/Makefile              |  1 -
>  tools/perf/Makefile.perf         |  6 ------
>  tools/power/acpi/Makefile.config |  3 ---
>  tools/scripts/Makefile.include   | 18 ++++++++++++++++++
>  tools/spi/Makefile               |  2 --
>  tools/usb/Makefile               |  1 -
>  tools/vm/Makefile                |  1 -
>  tools/wmi/Makefile               |  1 -
>  13 files changed, 18 insertions(+), 22 deletions(-)
> 
> diff --git a/tools/cgroup/Makefile b/tools/cgroup/Makefile
> index 860fa151640a..ffca068e4a76 100644
> --- a/tools/cgroup/Makefile
> +++ b/tools/cgroup/Makefile
> @@ -1,7 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  # Makefile for cgroup tools
>  
> -CC = $(CROSS_COMPILE)gcc
>  CFLAGS = -Wall -Wextra
>  
>  all: cgroup_event_listener
> diff --git a/tools/gpio/Makefile b/tools/gpio/Makefile
> index 805a2c0cf4cd..240eda014b37 100644
> --- a/tools/gpio/Makefile
> +++ b/tools/gpio/Makefile
> @@ -12,8 +12,6 @@ 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 := lsgpio gpio-hammer gpio-event-mon
> diff --git a/tools/hv/Makefile b/tools/hv/Makefile
> index 31503819454d..68c2d7b059b3 100644
> --- a/tools/hv/Makefile
> +++ b/tools/hv/Makefile
> @@ -1,7 +1,6 @@
>  # 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)
>  
> diff --git a/tools/iio/Makefile b/tools/iio/Makefile
> index a08e7a47d6a3..332ed2f6c2c2 100644
> --- a/tools/iio/Makefile
> +++ b/tools/iio/Makefile
> @@ -12,8 +12,6 @@ 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 := iio_event_monitor lsiio iio_generic_buffer
> diff --git a/tools/laptop/freefall/Makefile b/tools/laptop/freefall/Makefile
> index 5f758c489a20..b572d94255f6 100644
> --- a/tools/laptop/freefall/Makefile
> +++ b/tools/laptop/freefall/Makefile
> @@ -2,7 +2,6 @@
>  PREFIX ?= /usr
>  SBINDIR ?= sbin
>  INSTALL ?= install
> -CC = $(CROSS_COMPILE)gcc
>  
>  TARGET = freefall
>  
> diff --git a/tools/leds/Makefile b/tools/leds/Makefile
> index c379af003807..7b6bed13daaa 100644
> --- a/tools/leds/Makefile
> +++ b/tools/leds/Makefile
> @@ -1,7 +1,6 @@
>  # 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
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index 68cf1360a3f3..3035ce5f6b36 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -144,12 +144,6 @@ define allow-override
>      $(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
> diff --git a/tools/power/acpi/Makefile.config b/tools/power/acpi/Makefile.config
> index a1883bbb0144..2cccbba64418 100644
> --- a/tools/power/acpi/Makefile.config
> +++ b/tools/power/acpi/Makefile.config
> @@ -56,9 +56,6 @@ INSTALL_SCRIPT = ${INSTALL_PROGRAM}
>  # 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
> diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
> index 3fab179b1aba..09b2d0f07f66 100644
> --- a/tools/scripts/Makefile.include
> +++ b/tools/scripts/Makefile.include
> @@ -42,6 +42,24 @@ EXTRA_WARNINGS += -Wformat
>  
>  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,CXX,$(CROSS_COMPILE)strip)
> +
>  ifeq ($(CC_NO_CLANG), 1)
>  EXTRA_WARNINGS += -Wstrict-aliasing=3
>  endif
> diff --git a/tools/spi/Makefile b/tools/spi/Makefile
> index 90615e10c79a..815d15589177 100644
> --- a/tools/spi/Makefile
> +++ b/tools/spi/Makefile
> @@ -11,8 +11,6 @@ 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
> diff --git a/tools/usb/Makefile b/tools/usb/Makefile
> index 4e6506078494..01d758d73b6d 100644
> --- a/tools/usb/Makefile
> +++ b/tools/usb/Makefile
> @@ -1,7 +1,6 @@
>  # 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
> diff --git a/tools/vm/Makefile b/tools/vm/Makefile
> index be320b905ea7..20f6cf04377f 100644
> --- a/tools/vm/Makefile
> +++ b/tools/vm/Makefile
> @@ -6,7 +6,6 @@ TARGETS=page-types slabinfo page_owner_sort
>  LIB_DIR = ../lib/api
>  LIBS = $(LIB_DIR)/libapi.a
>  
> -CC = $(CROSS_COMPILE)gcc
>  CFLAGS = -Wall -Wextra -I../lib/
>  LDFLAGS = $(LIBS)
>  
> diff --git a/tools/wmi/Makefile b/tools/wmi/Makefile
> index e664f1167388..e0e87239126b 100644
> --- a/tools/wmi/Makefile
> +++ b/tools/wmi/Makefile
> @@ -2,7 +2,6 @@ PREFIX ?= /usr
>  SBINDIR ?= sbin
>  INSTALL ?= install
>  CFLAGS += -D__EXPORTED_HEADERS__ -I../../include/uapi -I../../include
> -CC = $(CROSS_COMPILE)gcc
>  
>  TARGET = dell-smbios-example
>  
> -- 
> 2.11.0
>