On Sun, Feb 28, 2021 at 03:10:28PM +0900, Masahiro Yamada wrote:
> Since commit f2f02ebd8f38 ("kbuild: improve cc-option to clean up all
> temporary files"), running 'make kernelversion' in a read-only source
> tree emits a bunch of warnings:
>
> mkdir: cannot create directory '.tmp_12345': Permission denied
>
> Non-build targets such as kernelversion, clean, help, etc. do not
> need to evaluate $(call cc-option,) and friends. Do not include
> Makefile.compiler so $(call cc-option,) becomes no-op.
>
> This not only fix the warnings, but also runs non-build targets much
> faster.
>
> Basically, all installation targets should also be non-build targets.
> Unfortunately, vdso_install requires the compiler because it builds
> vdso before installtion. This is a problem that must be fixed by a
> separate patch.
>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> ---
>
> I am not adding Reported-by for now because a reporter sent me
> an email privately.
>
> If he allows me to add Reported-by, I will add it to record
> the credit.
>
> (Perhaps, another person might have reported a similar issue
> somewhere, but my memory is obsure. I cannot recall it.)
>
>
> Makefile | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index eec7a94f5c33..20724711dc71 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -263,6 +263,10 @@ no-dot-config-targets := $(clean-targets) \
> $(version_h) headers headers_% archheaders archscripts \
> %asm-generic kernelversion %src-pkg dt_binding_check \
> outputmakefile
> +# Installation targets should not require compiler. Unfortunately, vdso_install
> +# is an exception where build artifacts may be updated. This must be fixed.
> +no-compiler-targets := $(no-dot-config-targets) install dtbs_install \
> + headers_install modules_install kernelrelease image_name
> no-sync-config-targets := $(no-dot-config-targets) %install kernelrelease \
> image_name
> single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.s %.symtypes %/
> @@ -270,6 +274,7 @@ single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.s %.symtypes %/
> config-build :=
> mixed-build :=
> need-config := 1
> +need-compiler := 1
> may-sync-config := 1
> single-build :=
>
> @@ -279,6 +284,12 @@ ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
> endif
> endif
>
> +ifneq ($(filter $(no-compiler-targets), $(MAKECMDGOALS)),)
> + ifeq ($(filter-out $(no-compiler-targets), $(MAKECMDGOALS)),)
> + need-compiler :=
> + endif
> +endif
> +
> ifneq ($(filter $(no-sync-config-targets), $(MAKECMDGOALS)),)
> ifeq ($(filter-out $(no-sync-config-targets), $(MAKECMDGOALS)),)
> may-sync-config :=
> @@ -584,7 +595,9 @@ endif
>
> # Include this also for config targets because some architectures need
> # cc-cross-prefix to determine CROSS_COMPILE.
> +ifdef need-compiler
> include $(srctree)/scripts/Makefile.compiler
> +endif
>
> ifdef config-build
> # ===========================================================================
> --
> 2.27.0
>
Hi Masahiro,
I see a new warning in my builds on arm64 now when running
'modules_install' or 'dtbs_install' because ld-option evaluates to
nothing, which triggers the warning in arch/arm64/Makefile:
$ make -skj"$(nproc)" \
ARCH=arm64 \
CROSS_COMPILE=aarch64-linux- \
INSTALL_DTBS_PATH=rootfs \
INSTALL_MOD_PATH=rootfs \
O=build/arm64 \
distclean defconfig all modules_install dtbs_install
...
/home/nathan/cbl/src/linux-next/arch/arm64/Makefile:25: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum
/home/nathan/cbl/src/linux-next/arch/arm64/Makefile:25: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum
$ sed -n '23,29p' arch/arm64/Makefile
ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
ifeq ($(call ld-option, --fix-cortex-a53-843419),)
$(warning ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum)
else
LDFLAGS_vmlinux += --fix-cortex-a53-843419
endif
endif
I am not sure how this should be resolved, hence just the report.
Cheers,
Nathan
