给树莓派3B+构建Linux时添加gcc

给树莓派 3B+ 构建 Linux 时想顺便添加 gcc，反正都是玩儿么。

不过根据 Buildroot 官方文档，从 Buildroot-2012.11 开始，对 native gcc 的支持就停止了。yocto 又太复杂了，只能在网上找添加目标 gcc 包的方法。

可能因为没什么用，很难找，找了一圈，最终在一个国外学校的网站上搜到了：Buildroot and compiler on target。

最终过程如下：

打补丁

git clone https://gitee.com/mirrors/buildroot.git

wget https://luplab.cs.ucdavis.edu/assets/buildroot-gcc/gcc-target.patch

git apply --stat ../gcc-target.patch
git apply --check ../gcc-target.patch
git apply ../gcc-target.patch

似乎应用不了，reset 到 2021.08-rc1 也不行。
算了，直接添加好了。

添加 hash 列表

添加文件 hash 值，用于下载校验

cd package/gcc/gcc-target/
ln -s ../gcc.hash gcc-target.hash

添加 mk 文件

添加 mk 文件，用于编译

nano package/gcc/gcc-target/gcc-target.mk

内容如下

################################################################################
#
# gcc-target
#
################################################################################

GCC_TARGET_VERSION = $(GCC_VERSION)
GCC_TARGET_SITE = $(GCC_SITE)
GCC_TARGET_SOURCE = $(GCC_SOURCE)

# Use the same archive as gcc-initial and gcc-final
GCC_TARGET_DL_SUBDIR = gcc

GCC_TARGET_DEPENDENCIES = gmp mpfr mpc

# First, we use HOST_GCC_COMMON_MAKE_OPTS to get a lot of correct flags (such as
# the arch, abi, float support, etc.) which are based on the config used to
# build the internal toolchain
GCC_TARGET_CONF_OPTS = $(HOST_GCC_COMMON_CONF_OPTS)
# Then, we modify incorrect flags from HOST_GCC_COMMON_CONF_OPTS
GCC_TARGET_CONF_OPTS += \
	--with-sysroot=/ \
	--with-build-sysroot=$(STAGING_DIR) \
	--disable-__cxa_atexit \
	--with-gmp=$(STAGING_DIR) \
	--with-mpc=$(STAGING_DIR) \
	--with-mpfr=$(STAGING_DIR)
# Then, we force certain flags that may appear in HOST_GCC_COMMON_CONF_OPTS
GCC_TARGET_CONF_OPTS += \
	--disable-libquadmath \
	--disable-libsanitizer \
	--disable-plugin \
	--disable-lto
# Finally, we add some of our own flags
GCC_TARGET_CONF_OPTS += \
	--enable-languages=c \
	--disable-boostrap \
	--disable-libgomp \
	--disable-nls \
	--disable-libmpx \
	--disable-gcov \
	$(EXTRA_TARGET_GCC_CONFIG_OPTIONS)

GCC_TARGET_CONF_ENV = $(HOST_GCC_COMMON_CONF_ENV)

GCC_TARGET_MAKE_OPTS += $(HOST_GCC_COMMON_MAKE_OPTS)

# Install standard C headers (from glibc)
define GCC_TARGET_INSTALL_HEADERS
	cp -r $(STAGING_DIR)/usr/include $(TARGET_DIR)/usr
endef
GCC_TARGET_POST_INSTALL_TARGET_HOOKS += GCC_TARGET_INSTALL_HEADERS

# Install standard C libraries (from glibc)
GCC_TARGET_GLIBC_LIBS = \
	*crt*.o *_nonshared.a \
	libBrokenLocale.so libanl.so libbfd.so libc.so libcrypt.so libdl.so \
	libm.so libnss_compat.so libnss_db.so libnss_files.so libnss_hesiod.so \
	libpthread.so libresolv.so librt.so libthread_db.so libutil.so

define GCC_TARGET_INSTALL_LIBS
	for libpattern in $(GCC_TARGET_GLIBC_LIBS); do \
		$(call copy_toolchain_lib_root,$$libpattern) ; \
	done
endef
GCC_TARGET_POST_INSTALL_TARGET_HOOKS += GCC_TARGET_INSTALL_LIBS

# Remove unnecessary files (extra links to gcc binaries, and libgcc which is
# already in `/lib`)
define GCC_TARGET_RM_FILES
	rm -f $(TARGET_DIR)/usr/bin/$(ARCH)-buildroot-linux-gnu-gcc*
	rm -f $(TARGET_DIR)/usr/lib/libgcc_s*.so*
	rm -f $(TARGET_DIR)/usr/$(ARCH)-buildroot-linux-gnu/lib/ldscripts/elf32*
	rm -f $(TARGET_DIR)/usr/$(ARCH)-buildroot-linux-gnu/lib/ldscripts/elf64b*
endef
GCC_TARGET_POST_INSTALL_TARGET_HOOKS += GCC_TARGET_RM_FILES

$(eval $(autotools-package))

添加目标包配置脚本

nano package/gcc/Config.in

内容如下

config BR2_PACKAGE_GCC_TARGET
	bool "gcc"
	depends on BR2_TOOLCHAIN_BUILDROOT
	select BR2_PACKAGE_BINUTILS
	select BR2_PACKAGE_BINUTILS_TARGET
	select BR2_PACKAGE_GMP
	select BR2_PACKAGE_MPFR
	select BR2_PACKAGE_MPC
	help
	  If you want the target system to be able to run
	  binutils/gcc and compile native code, say Y here.

config BR2_EXTRA_TARGET_GCC_CONFIG_OPTIONS
	string "Additional target gcc options"
	default ""
	depends on BR2_PACKAGE_GCC_TARGET
	help
	  Any additional target gcc options you may want to include....
	  Including, but not limited to --disable-checking etc.
	  Refer to */configure in your gcc sources.
      

添加目标包引用

nano package/Config.in

在 Develope tools 下面添加

source "package/gcc/Config.in"

包含头文件

安装到目标时将头文件包含进去

nano Makefile

修改如下

rm -rf $(TARGET_DIR)/usr/include $(TARGET_DIR)/usr/share/aclocal \
替换为
rm -rf $(TARGET_DIR)/usr/share/aclocal \

\( -name '*.a' -o -name '*.la' -o -name '*.prl' \) -print0 | xargs -0 rm -f
替换为
\( -name '*.la' -o -name '*.prl' \) -print0 | xargs -0 rm -f

重新配置

make menuconfig

修改如下

Target packages ->Development tools，添加 gcc
Filesystem ->images exact size，改为 500M
Build options ->strip target binaries，取消

重新编译

make -j8