The source for the Linux kernel used in Windows Subsystem for Linux 2 (WSL2)
Перейти к файлу
Masahiro Yamada 392885ee82 kbuild: let fixdep directly write to .*.cmd files
Currently, fixdep writes dependencies to .*.tmp, which is renamed to
.*.cmd after everything succeeds. This is a very safe way to avoid
corrupted .*.cmd files. The if_changed_dep has carried this safety
mechanism since it was added in 2002.

If fixdep fails for some reasons or a user terminates the build while
fixdep is running, the incomplete output from the fixdep could be
troublesome.

This is my insight about some bad scenarios:

[1] If the compiler succeeds to generate *.o file, but fixdep fails
    to write necessary dependencies to .*.cmd file, Make will miss
    to rebuild the object when headers or CONFIG options are changed.
    In this case, fixdep should not generate .*.cmd file at all so
    that 'arg-check' will surely trigger the rebuild of the object.

[2] A partially constructed .*.cmd file may not be a syntactically
    correct makefile. The next time Make runs, it would include it,
    then fail to parse it. Once this happens, 'make clean' is be the
    only way to fix it.

In fact, [1] is no longer a problem since commit 9c2af1c737 ("kbuild:
add .DELETE_ON_ERROR special target"). Make deletes a target file on
any failure in its recipe. Because fixdep is a part of the recipe of
*.o target, if it fails, the *.o is deleted anyway. However, I am a
bit worried about the slight possibility of [2].

So, here is a solution. Let fixdep directly write to a .*.cmd file,
but allow makefiles to include it only when its corresponding target
exists.

This effectively reverts commit 2982c95357 ("kbuild: remove redundant
$(wildcard ...) for cmd_files calculation"), and commit 00d78ab2ba
("kbuild: remove dead code in cmd_files calculation in top Makefile")
because now we must check the presence of targets.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-12-01 23:13:14 +09:00
Documentation kbuild: announce removal of SUBDIRS if used 2018-12-01 22:21:56 +09:00
LICENSES
arch kbuild: fix UML build error with CONFIG_GCC_PLUGINS 2018-12-01 22:21:59 +09:00
block for-linus-20181109 2018-11-09 16:31:51 -06:00
certs
crypto
drivers kbuild: announce removal of SUBDIRS if used 2018-12-01 22:21:56 +09:00
firmware
fs for-4.20-rc1-tag 2018-11-11 16:54:38 -06:00
include Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-11-11 16:41:50 -06:00
init
ipc
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-11-11 16:37:41 -06:00
lib lib/raid6: Fix arm64 test build 2018-11-06 17:12:44 +00:00
mm memory_hotplug: cond_resched in __remove_pages 2018-11-03 10:09:38 -07:00
net act_mirred: clear skb->tstamp on redirect 2018-11-11 10:21:31 -08:00
samples kbuild: announce removal of SUBDIRS if used 2018-12-01 22:21:56 +09:00
scripts kbuild: let fixdep directly write to .*.cmd files 2018-12-01 23:13:14 +09:00
security + Features/Improvements 2018-11-02 10:04:26 -07:00
sound ALSA: hda - Fix incorrect clearance of thinkpad_acpi hooks 2018-11-06 16:33:53 +01:00
tools perf/urgent improvements and fixes: 2018-11-06 20:03:11 +01:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap mailmap: Update email for Punit Agrawal 2018-11-05 10:02:11 +00:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2018-11-10 06:57:34 -06:00
Makefile kbuild: let fixdep directly write to .*.cmd files 2018-12-01 23:13:14 +09:00
README

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.

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.