@H_404_1@我运行一个CI服务器,用于构建自定义Linux内核. CI服务器功能不强,每个构建的时间限制为3h.为了在这个限制内工作,我有了使用ccache缓存内核构建的想法.我希望我可以在每个次要版本发布时创建一个缓存,并将其重新用于补丁版本,例如：我有一个我为4.18制作的缓存,我想用于所有4.18.x内核.
@H_404_1@删除构建时间戳后,这适用于我正在构建的确切内核版本.对于上面引用的4.18内核,在CI上构建它会提供以下统计信息：
@H_404_1@
$ccache -s
cache directory
primary config
secondary config (readonly) /etc/ccache.conf
stats zero time Thu Aug 16 14:36:22 2018
cache hit (direct) 17812
cache hit (preprocessed) 38
cache miss 0
cache hit rate 100.00 %
called for link 3
called for preprocessing 29039
unsupported code directive 4
no input file 2207
cleanups performed 0
files in cache 53652
cache size 1.4 GB
max cache size 5.0 GB
cache directory
primary config
secondary config (readonly) /etc/ccache.conf
stats zero time Thu Aug 16 10:36:22 2018
cache hit (direct) 0
cache hit (preprocessed) 233
cache miss 17658
cache hit rate 1.30 %
called for link 3
called for preprocessing 29039
unsupported code directive 4
no input file 2207
cleanups performed 0
files in cache 90418
cache size 2.4 GB
max cache size 5.0 GB
最佳答案
有include / generated / uapi / linux / version.h头文件(在顶级Makefile https://elixir.bootlin.com/linux/v4.16.18/source/Makefile中生成)
@H_404_1@其中包括精确的内核版本作为宏：
@H_404_1@
原文链接：https://www.f2er.com/linux/440987.htmlversion_h := include/generated/uapi/linux/version.h
old_version_h := include/linux/version.h
define filechk_version.h
(echo \#define LINUX_VERSION_CODE $(shell \
expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 0$(SUBLEVEL)); \
echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))';)
endef
$(version_h): $(srctree)/Makefile FORCE
$(call filechk,version.h)
$(Q)rm -f $(old_version_h)
#define LINUX_VERSION_CODE 266258
#define KERNEL_VERSION(a,c) (((a) << 16) + ((b) << 8) + (c))
@H_404_1@The way to do this to compare the macro@H_404_1@如何包含version.h？示例模块包括< linux / kernel.h> < LINUX /&module.h中GT;和< linux / modversions.h>,其中一个文件可能间接包含全局version.h.大多数甚至所有内核源代码都包含version.h. @H_404_1@比较构建时间戳时,可能会重新生成version.h并禁用ccache.当忽略时间戳时,LINUX_VERSION_CODE仅对完全相同的Linux内核版本相同,并且对于下一个补丁级别进行更改. @H_404_1@更新：检查一些内核对象编译的gcc -H输出,会有另一个带有完整内核版本宏定义的头.例如：include / generated / utsrelease.h(UTS_RELEASE宏),include / generated / autoconf.h(CONFIG_VERSION_SIGNATURE). @H_404_1@或者甚至在两个补丁级别之间进行相同内核对象编译的gcc -E预处理,并比较生成的文本.使用最简单的linux模块,我直接在gcc命令行中包含./include/linux/kconfig.h,它包含include / generated / autoconf.h(但这在-H输出中不可见,是bug还是功能GCC？). @H_404_1@https://patchwork.kernel.org/patch/9326051/ @H_404_1@LINUX_VERSION_CODEto the macroKERNEL_VERSION. In versiona.b.cof the kernel,the value of this macro would be2^{16}a+2^{8}b+c. Be aware that this macro is not defined for kernel 2.0.35 and earlier,so if you want to write modules that support really old kernels
@H_404_1@… because the top Makefile forces to include it with: @H_404_1@06002@H_404_1@它实际上是：https://elixir.bootlin.com/linux/v4.16.18/source/Makefile @H_404_1@
# Use USERINCLUDE when you must reference the UAPI directories only.
USERINCLUDE := \
-I$(srctree)/arch/$(SRCARCH)/include/uapi \
-I$(objtree)/arch/$(SRCARCH)/include/generated/uapi \
-I$(srctree)/include/uapi \
-I$(objtree)/include/generated/uapi \
-include $(srctree)/include/linux/kconfig.h
# Use LINUXINCLUDE when you must reference the include/ directory.
# Needed to be compatible with the O= option
LINUXINCLUDE := \
-I$(srctree)/arch/$(SRCARCH)/include \
-I$(objtree)/arch/$(SRCARCH)/include/generated \
$(if $(KBUILD_SRC),-I$(srctree)/include) \
-I$(objtree)/include \
$(USERINCLUDE)
c_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)
