From: Sami Tolvanen <samitolvanen@google.com>
To: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: clang-built-linux@googlegroups.com, keescook@chromium.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
masahiroy@kernel.org, michal.lkml@markovi.net, nathan@kernel.org,
ndesaulniers@google.com, yj.chiang@mediatek.com
Subject: Re: [PATCH v3 1/2] Kbuild: lto: add CONFIG_MAKE_VERSION
Date: Wed, 7 Jul 2021 10:02:24 -0700 [thread overview]
Message-ID: <CABCJKufWcp6Hx=8btz6pDNcKvQ21n4BSPZ7cp1Tzhxt0+pQOmw@mail.gmail.com> (raw)
In-Reply-To: <20210706090607.19421-1-lecopzer.chen@mediatek.com>
On Tue, Jul 6, 2021 at 2:06 AM Lecopzer Chen <lecopzer.chen@mediatek.com> wrote:
>
> > On Sun, Jul 4, 2021 at 7:03 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > On Fri, Jul 2, 2021 at 12:29 PM Lecopzer Chen
> > > <lecopzer.chen@mediatek.com> wrote:
> > > >
> > > > To check the GNU make version. Used by the LTO Kconfig.
> > > >
> > > > LTO with MODVERSIONS will fail in generating correct CRC because
> > > > the makefile rule doesn't work for make with version 3.8X.[1]
> > > >
> > > > Thus we need to check make version during selecting on LTO Kconfig.
> > > > Add CONFIG_MAKE_VERSION which means MAKE_VERSION in canonical digits
> > > > for arithmetic comparisons.
> > > >
> > > > [1] https://lore.kernel.org/lkml/20210616080252.32046-1-lecopzer.chen@mediatek.com/
> > > > Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
> > > > ---
> > >
> > >
> > > NACK.
> > >
> > > "Let's add MAKE_VERSION >= 40200 restriction
> > > just because I cannot write correct code that
> > > works for older Make" is a horrible idea.
> > >
> > > Also, Kconfig is supposed to check the compiler
> > > (or toolchains) capability, not host tool versions.
> >
> > I feel like requiring a Make that's half a decade old for a feature
> > that also requires a toolchain released last October ago isn't
> > entirely unreasonable.
> >
> > That being said, if Masahiro prefers not to rely on the wildcard
> > function's behavior here, which is a reasonable request, we could
> > simply use the shell to test for the file's existence:
> >
> > diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> > index 34d257653fb4..c6bd62f518ff 100644
> > --- a/scripts/Makefile.build
> > +++ b/scripts/Makefile.build
> > @@ -388,7 +388,7 @@ ifeq ($(CONFIG_LTO_CLANG) $(CONFIG_MODVERSIONS),y y)
> > cmd_update_lto_symversions = \
> > rm -f $@.symversions \
> > $(foreach n, $(filter-out FORCE,$^), \
> > - $(if $(wildcard $(n).symversions), \
> > + $(if $(shell test -s $(n).symversions && echo y), \
> > ; cat $(n).symversions >> $@.symversions))
> > else
> > cmd_update_lto_symversions = echo >/dev/null
> >
> > This is not quite as efficient as using wildcard, but should work with
> > older Make versions too. Thoughts?
> >
>
>
> I've tested this in both make-4.3 and 3.81, and the CRC is correct.
> But I'm not sure if anyone would have the "arg list too long" issue.
>
> Tested-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Thank you for testing. This should produce a command identical to the
wildcard version (with newer Make versions), so that shouldn't be an
issue. If nobody objects to this approach, would you mind putting this
into a proper patch and sending it as v4?
Sami
next prev parent reply other threads:[~2021-07-07 17:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-02 3:29 [PATCH v3 0/2] Kbuild: lto: add make version checking for MODVERSIONS Lecopzer Chen
2021-07-02 3:29 ` [PATCH v3 1/2] Kbuild: lto: add CONFIG_MAKE_VERSION Lecopzer Chen
2021-07-04 0:15 ` Nathan Chancellor
2021-07-05 2:02 ` Masahiro Yamada
2021-07-05 17:59 ` Sami Tolvanen
2021-07-06 9:06 ` Lecopzer Chen
2021-07-07 17:02 ` Sami Tolvanen [this message]
2021-07-09 8:25 ` Lecopzer Chen
2021-07-02 3:29 ` [PATCH v3 2/2] Kbuild: lto: add make version checking Lecopzer Chen
2021-07-04 0:16 ` Nathan Chancellor
2021-07-05 2:04 ` Masahiro Yamada
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