mainlining shenanigans
00c864f890
Currently, only syncconfig creates or updates include/config/auto.conf
and some other files. Other config targets create or update only the
.config file.
When you configure and build the kernel from a pristine source tree,
any config target is followed by syncconfig in the build stage since
include/config/auto.conf is missing.
We are moving compiler tests from Makefile to Kconfig. It means that
parsing Kconfig files will be more costly since Kconfig invokes the
compiler commands internally. Thus, we want to avoid invoking Kconfig
twice (one for *config to create the .config, and one for syncconfig
to synchronize the auto.conf). If auto.conf does not exist, we can
generate all configuration files in the first configuration stage,
which will save the syncconfig in the build stage.
Please note this should be done only when auto.conf is missing. If
*config blindly did this, time stamp files under include/config/ would
be unnecessarily touched, triggering unneeded rebuild of objects.
I assume a scenario like this:
1. You have a source tree that has already been built
with CONFIG_FOO disabled
2. Run "make menuconfig" to enable CONFIG_FOO
3. CONFIG_FOO turns out to be unnecessary.
Run "make menuconfig" again to disable CONFIG_FOO
4. Run "make"
In this case, include/config/foo.h should not be touched since there
is no change in CONFIG_FOO. The sync process should be delayed until
the user really attempts to build the kernel.
This commit has another motivation; I want to suppress the 'No such
file or directory' warning from the 'include' directive.
The top-level Makefile includes auto.conf with '-include' directive,
like this:
ifeq ($(dot-config),1)
-include include/config/auto.conf
endif
This looks strange because auto.conf is mandatory when dot-config is 1.
I guess only the reason of using '-include' is to suppress the warning
'include/config/auto.conf: No such file or directory' when building
from a clean tree. However, this has a side-effect; Make considers
the files included by '-include' are optional. Hence, Make continues
to build even if it fails to generate include/config/auto.conf. I will
change this in the next commit, but the warning message is annoying.
(At least, kbuild test robot reports it as a regression.)
With this commit, Kconfig will generate all configuration files together
with the .config and I guess it is a solution good enough to suppress
the warning.
Note:
GNU Make 4.2 or later does not display the warning from the 'include'
directive if include files are successfully generated. See GNU Make
commit 87a5f98d248f ("[SV 102] Don't show unnecessary include file
errors.") However, older GNU Make versions are still widely used.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.