Kbuild puts the objects listed in head-y at the head of vmlinux.
Conventionally, we do this for head*.S, which contains the kernel entry
point.
A counter approach is to control the section order by the linker script.
Actually, the code marked as __HEAD goes into the ".head.text" section,
which is placed before the normal ".text" section.
I do not know if both of them are needed. From the build system
perspective, head-y is not mandatory. If you can achieve the proper code
placement by the linker script only, it would be cleaner.
I collected the current head-y objects into head-object-list.txt. It is
a whitelist. My hope is it will be reduced in the long run.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
The objects placed at the head of vmlinux need special treatments:
- arch/$(SRCARCH)/Makefile adds them to head-y in order to place
them before other archives in the linker command line.
- arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of
obj-y to avoid them going into built-in.a.
This commit gets rid of the latter.
Create vmlinux.a to collect all the objects that are unconditionally
linked to vmlinux. The objects listed in head-y are moved to the head
of vmlinux.a by using 'ar m'.
With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y
for builtin objects.
There is no *.o that is directly linked to vmlinux. Drop unneeded code
in scripts/clang-tools/gen_compile_commands.py.
$(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested
by Nathan Chancellor [1].
[1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
V=1 (verbose build) shows commands executed by Make, but it may cause
misunderstanding.
For example, the following command shows the outstanding error message.
$ make V=1 INSTALL_PATH=/tmp install
test -e include/generated/autoconf.h -a -e include/config/auto.conf || ( \
echo >&2; \
echo >&2 " ERROR: Kernel configuration is invalid."; \
echo >&2 " include/generated/autoconf.h or include/config/auto.conf are missing.";\
echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it."; \
echo >&2 ; \
/bin/false)
unset sub_make_done; ./scripts/install.sh
It is not an error. Make just showed the recipe lines it has executed,
but people may think that 'make install' has failed.
Likewise, the combination of V=1 and O= shows confusing
"*** The source tree is not clean, please run 'make mrproper'".
Suppress such misleading logs.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Modpost generates .vmlinux.export.c and *.mod.c, which are prerequisites
of vmlinux and modules, respectively.
The modpost stage should be re-run when the modpost code is updated.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Currently, modpost is executed twice; first for vmlinux, second
for modules.
This commit merges them.
Current build flow
==================
1) build obj-y and obj-m objects
2) link vmlinux.o
3) modpost for vmlinux
4) link vmlinux
5) modpost for modules
6) link modules (*.ko)
The build steps 1) through 6) are serialized, that is, modules are
built after vmlinux. You do not get benefits of parallel builds when
scripts/link-vmlinux.sh is being run.
New build flow
==============
1) build obj-y and obj-m objects
2) link vmlinux.o
3) modpost for vmlinux and modules
4a) link vmlinux
4b) link modules (*.ko)
In the new build flow, modpost is invoked just once.
vmlinux and modules are built in parallel. One exception is
CONFIG_DEBUG_INFO_BTF_MODULES=y, where modules depend on vmlinux.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Move the build rules of vmlinux.o out of scripts/link-vmlinux.sh to
clearly separate 1) pre-modpost, 2) modpost, 3) post-modpost stages.
This will make further refactoring possible.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
.vmlinux.objs is used by modpost, so scripts/Makefile.modpost is
a better place to generate it.
It is used only when CONFIG_MODVERSIONS=y. It should be guarded
by "ifdef CONFIG_MODVERSIONS".
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Use the ordinary obj-y syntax to list subdirectories.
Note1:
Previously, the link order of lib-y depended on CONFIG_MODULES; lib-y
was linked before drivers-y when CONFIG_MODULES=y, otherwise after
drivers-y. This was a bug of commit 7273ad2b08 ("kbuild: link lib-y
objects to vmlinux forcibly when CONFIG_MODULES=y"), but it was not a
big deal after all. Now, all objects listed in lib-y are linked last,
irrespective of CONFIG_MODULES.
Note2:
Finally, the single target build in arch/*/lib/ works correctly. There was
a bug report about this. [1]
$ make ARCH=arm arch/arm/lib/findbit.o
CALL scripts/checksyscalls.sh
AS arch/arm/lib/findbit.o
[1]: https://lore.kernel.org/linux-kbuild/YvUQOwL6lD4%2F5%2FU6@shell.armlinux.org.uk/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Doing make V=1 binrpm-pkg results in:
Executing(%install): /bin/sh -e /var/tmp/rpm-tmp.EgV6qJ
+ umask 022
+ cd .
+ /bin/rm -rf /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x
+ /bin/mkdir -p /home/scgl/rpmbuild/BUILDROOT
+ /bin/mkdir /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x
+ mkdir -p /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x/boot
+ make -f ./Makefile image_name
+ cp test -e include/generated/autoconf.h -a -e include/config/auto.conf || ( \ echo >&2; \ echo >&2 " ERROR: Kernel configuration is invalid."; \ echo >&2 " include/generated/autoconf.h or include/config/auto.conf are missing.";\ echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it."; \ echo >&2 ; \ /bin/false) arch/s390/boot/bzImage /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x/boot/vmlinuz-6.0.0-rc5+
cp: invalid option -- 'e'
Try 'cp --help' for more information.
error: Bad exit status from /var/tmp/rpm-tmp.EgV6qJ (%install)
Because the make call to get the image name is verbose and prints
additional information.
Fixes: 993bdde945 ("kbuild: add image_name to no-sync-config-targets")
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Remove unused function argument, and there is
no logic changes.
Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Since commit 7b4537199a ("kbuild: link symbol CRCs at final link,
removing CONFIG_MODULE_REL_CRCS"), the module versioning on the
(non-upstreamed-yet) kvx Linux port is broken due to unexpected padding
for __crc_* symbols. The kvx GCC adds padding so u32 gets 8-byte
alignment instead of 4.
I do not know if this happens for upstream architectures in general,
but any compiler has the freedom to insert padding for faster access.
Use the inline assembler to directly specify the wanted data layout.
This is how we previously did before the breakage.
Link: https://lore.kernel.org/lkml/20220817161438.32039-1-ysionneau@kalray.eu/
Link: https://lore.kernel.org/linux-kbuild/31ce5305-a76b-13d7-ea55-afca82c46cf2@kalray.eu/
Fixes: 7b4537199a ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS")
Reported-by: Yann Sionneau <ysionneau@kalray.eu>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Yann Sionneau <ysionneau@kalray.eu>
The single target build has a subtle bug for the combination for
an individual file and a subdirectory.
[1] 'make kernel/fork.i' builds only kernel/fork.i
$ make kernel/fork.i
CALL scripts/checksyscalls.sh
DESCEND objtool
CPP kernel/fork.i
[2] 'make kernel/' builds only under the kernel/ directory.
$ make kernel/
CALL scripts/checksyscalls.sh
DESCEND objtool
CC kernel/fork.o
CC kernel/exec_domain.o
[snip]
CC kernel/rseq.o
AR kernel/built-in.a
But, if you try to do [1] and [2] in a single command, you will get
only [1] with a weird log:
$ make kernel/fork.i kernel/
CALL scripts/checksyscalls.sh
DESCEND objtool
CPP kernel/fork.i
make[2]: Nothing to be done for 'kernel/'.
With 'make kernel/fork.i kernel/', you should get both [1] and [2].
Rewrite the single target build.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Remove the bash build dependency for those who otherwise do not
have it installed. This also provides a significant speedup:
$ make defconfig
$ make yes2modconfig
...
$ find . -name "*.o" | grep -v vmlinux | wc
3169 3169 89615
$ export NM=nm
$ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1
./scripts/check-local-export'
Without patch:
0m15.90s real 0m12.17s user 0m05.28s system
With patch:
dash + nawk
0m02.16s real 0m02.92s user 0m00.34s system
dash + busybox awk
0m02.36s real 0m03.36s user 0m00.34s system
dash + gawk
0m02.07s real 0m03.26s user 0m00.32s system
bash + gawk
0m03.55s real 0m05.00s user 0m00.54s system
Signed-off-by: Owen Rafferty <owen@owenrafferty.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Minimize the scope of LC_ALL=C like before commit 87c94bfb8a ("kbuild:
override build timestamp & version").
Give LC_ALL=C to '$LD -v' to get the consistent version output, as commit
bcbcf50f52 ("kbuild: fix ld-version.sh to not be affected by locale")
mentioned the LD version is affected by locale.
While I was here, I merged two sed invocations.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Now that UTS_VERSION was separated out, this header can be generated
much earlier, and probably the top Makefile is a better place to do it
than init/Makefile.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Kbuild builds init/built-in.a twice; first during the ordinary
directory descending, second from scripts/link-vmlinux.sh.
We do this because UTS_VERSION contains the build version and the
timestamp. We cannot update it during the normal directory traversal
since we do not yet know if we need to update vmlinux. UTS_VERSION is
temporarily calculated, but omitted from the update check. Otherwise,
vmlinux would be rebuilt every time.
When Kbuild results in running link-vmlinux.sh, it increments the
version number in the .version file and takes the timestamp at that
time to really fix UTS_VERSION.
However, updating the same file twice is a footgun. To avoid nasty
timestamp issues, all build artifacts that depend on init/built-in.a
are atomically generated in link-vmlinux.sh, where some of them do not
need rebuilding.
To fix this issue, this commit changes as follows:
[1] Split UTS_VERSION out to include/generated/utsversion.h from
include/generated/compile.h
include/generated/utsversion.h is generated just before the
vmlinux link. It is generated under include/generated/ because
some decompressors (s390, x86) use UTS_VERSION.
[2] Split init_uts_ns and linux_banner out to init/version-timestamp.c
from init/version.c
init_uts_ns and linux_banner contain UTS_VERSION. During the ordinary
directory descending, they are compiled with __weak and used to
determine if vmlinux needs relinking. Just before the vmlinux link,
they are compiled without __weak to embed the real version and
timestamp.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This is unneeded since commit 073a9ecb3a ("init/version.c: remove
Version_<LINUX_VERSION_CODE> symbol").
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Remove the potentially invalid modules.order instead of using
the temporary file.
Also, KBUILD_MODULES is don't care for single builds. No need to
cancel it.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The dependency, "modules: modules_check" is specified twice.
Commit 1a998be620 ("kbuild: check module name conflict for external
modules as well") missed to clean it up.
'PHONY += modules' also appears twice.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
