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Subject[PATCH 0/2] Kbuild: lto: add make version checking
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LTO with MODVERSION will fail in generating correct CRC because
the makefile rule doesn't work for make with version 3.8X.

Refer to [1]:
> When building modules(CONFIG_...=m), I found some of module versions
> are incorrect and set to 0.
> This can be found in build log for first clean build which shows

> WARNING: EXPORT symbol "XXXX" [drivers/XXX/XXX.ko] version generation failed,
> symbol will not be versioned.

> But in second build(incremental build), the WARNING disappeared and the
> module version becomes valid CRC and make someone who want to change
> modules without updating kernel image can't insert their modules.

> The problematic code is
> + $(foreach n, $(filter-out FORCE,$^), \
> + $(if $(wildcard $(n).symversions), \
> + ; cat $(n).symversions >> $@.symversions))

The issue fixed when make version upgrading to 4.2.

Thus we need to check make version during selecting on LTO Kconfig.
The MAKE_VERSION_INT means MAKE_VERSION in canonical digits integer and
implemnted by imitating CLANG_VERSION.

[1] https://lore.kernel.org/lkml/20210616080252.32046-1-lecopzer.chen@mediatek.com/
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>

Lecopzer Chen (2):
Kbuild: lto: add make-version macros
Kbuild: lto: add make version checking

Makefile | 2 +-
arch/Kconfig | 1 +
init/Kconfig | 4 ++++
scripts/Kconfig.include | 3 +++
scripts/make-version.sh | 13 +++++++++++++
5 files changed, 22 insertions(+), 1 deletion(-)
create mode 100755 scripts/make-version.sh

--
2.18.0

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