linux-kernel - Re: [PATCH] kbuild: add script check for cross compilation utilities

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Date:   Sun, 12 May 2019 12:04:48 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kbuild: add script check for cross compilation utilities

On Sat, May 11, 2019 at 11:25 AM Nathan Chancellor
<natechancellor@...il.com> wrote:
>
> Few comments below but nothing major, this seems to work fine as is.
>
> On Thu, May 09, 2019 at 01:19:21PM -0700, 'Nick Desaulniers' via Clang Built Linux wrote:
> > When cross compiling via setting CROSS_COMPILE, if the prefixed tools
> > are not found, then the host utilities are often instead invoked, and
> > produce often difficult to understand errors.  This is most commonly the
> > case for developers new to cross compiling the kernel that have yet to
> > install the proper cross compilation toolchain. Rather than charge
> > headlong into a build that will fail obscurely, check that the tools
> > exist before starting to compile, and fail with a friendly error
> > message.
>
> This part of the commit message makes it sound like this is a generic
> problem when it is actually specific to clang. make will fail on its
> own when building with gcc if CROSS_COMPILE is not properly set (since
> gcc won't be found).
>
> On a side note, seems kind of odd that clang falls back to the host
> tools when a non-host --target argument is used... (how in the world is
> that expected to work?)


I agree.
Failure is much better than falling back to host tools.


-- 
Best Regards
Masahiro Yamada