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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Fri, 19 Aug 2022 17:40:17 +0900
Message-ID: <CAK7LNAQTHO3Za9UpeCCkdNo-mQS8ORgbfwXCJKKr4FCZ3VqT2Q@mail.gmail.com>
Subject: Re: [PATCH] init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash
To:     Richard Purdie <richard.purdie@linuxfoundation.org>
Cc:     Randy Dunlap <rdunlap@infradead.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Aug 19, 2022 at 6:46 AM Richard Purdie
<richard.purdie@linuxfoundation.org> wrote:
>
> On Fri, 2022-08-19 at 04:31 +0900, Masahiro Yamada wrote:
> > On Thu, Aug 18, 2022 at 6:14 PM Richard Purdie
> > <richard.purdie@linuxfoundation.org> wrote:
> > >
> > > This problem is a little more subtle.
> > >
> > > As far as I could work out, exec() is used on entries like this in
> > > kConfig. exec() falls back to /bin/sh so it is hard to see where this
> > > would be changed to be /bin/bash.
> >
> >
> >
> > Kconfig uses popen() to execute a shell command.
> >
> > See do_shell() in scripts/kconfig/preprocess.c
> >
> > popen(3) says that
> > "the command is passed to /bin/sh using the -c flag.
> > interpretation, if any, is performed by the shell."
> >
> > GNU Make is the same.
> > Make uses /bin/sh to execute commands in
> > recipe lines and $(shell ...) functions.
> > You can change the default shell via 'SHELL' variable.
>
> That makes sense. I don't think we can easily change the shell popen()
> uses.
>
> >
> > BTW, Richard is here, so let me ask about BitBake.
> >
> > The manual [3] clearly says:
> >
> > "When you create these types of functions in your recipe or class files,
> > you need to follow the shell programming rules. The scripts are
> > executed by /bin/sh,
> > which may not be a bash shell but might be something such as dash.
> > You should not use Bash-specific script (bashisms)"
> >
> > I just thought BitBake ran shell code in bash before,
> > but I might have misunderstood.
> > Do OE/Yocto allow only POSIX shell code?
>
> Bitbake runs shell code with /bin/sh so we don't allow bashisms and
> that has always been the case.
>
> Like this case in the kernel, we do get people submitting changes which
> were only tested with bash which can be frustrating but the manual and
> our policy is quite clear. We just fix any that do creep through and
> have test systems that have dash to try and catch them too.
>
> Cheers,
>
> Richard


Thanks.
So, Bitbake is the same approach as the kernel.


This is a patch set to use bash forcibly. FWIW.

https://lore.kernel.org/lkml/20220819065604.295572-1-masahiroy@kernel.org/


-- 
Best Regards
Masahiro Yamada