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From: Nick Desaulniers <ndesaulniers@google.com>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Nathan Chancellor <natechancellor@gmail.com>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	Michal Marek <michal.lkml@markovi.net>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Stephen Hines <srhines@google.com>
Subject: Re: [PATCH] kbuild: add script check for cross compilation utilities
Date: Mon, 13 May 2019 11:04:02 -0700	[thread overview]
Message-ID: <CAKwvOd=+h8oxyRwPPoHajXM_JicfZ3YV2rhw6Ee06xh5=82fEw@mail.gmail.com> (raw)
In-Reply-To: <CAK7LNARB_ds9-dF9n1jHD==JRWsnPYNGoKxLqb+FwKvTTC0bLQ@mail.gmail.com>

On Sat, May 11, 2019 at 8:05 PM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> On Sat, May 11, 2019 at 11:25 AM Nathan Chancellor
> <natechancellor@gmail.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.

It was probably assumed that the default case is usually not cross
compilation.  But I think we can add a check to Clang's driver where
`if target_triple != host_triple then don't invoke host tools`.

-- 
Thanks,
~Nick Desaulniers

  reply	other threads:[~2019-05-13 18:04 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-09 20:19 Nick Desaulniers
2019-05-11  2:24 ` Nathan Chancellor
2019-05-12  3:04   ` Masahiro Yamada
2019-05-13 18:04     ` Nick Desaulniers [this message]
2019-05-12  2:21 ` Masahiro Yamada

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