linux-kernel - Re: [PATCH] ARC: Don't set CROSS

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Message-ID: <20181018124401.GB1451@kroah.com>
Date:   Thu, 18 Oct 2018 14:44:01 +0200
From:   "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
To:     Alexey Brodkin <alexey.brodkin@...opsys.com>
Cc:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Vineet Gupta <vineet.gupta1@...opsys.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Rob Herring <robh@...nel.org>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>
Subject: Re: [PATCH] ARC: Don't set CROSS_COMPILE in arch's Makefile

On Wed, Oct 17, 2018 at 02:33:02PM +0000, Alexey Brodkin wrote:
> Hello,
> 
> > -----Original Message-----
> > From: Alexey Brodkin [mailto:abrodkin@...opsys.com]
> > Sent: Sunday, September 16, 2018 11:48 PM
> > To: linux-snps-arc@...ts.infradead.org
> > Cc: linux-kernel@...r.kernel.org; Vineet Gupta <vgupta@...opsys.com>; Alexey Brodkin <abrodkin@...opsys.com>; Masahiro
> > Yamada <yamada.masahiro@...ionext.com>; Rob Herring <robh@...nel.org>
> > Subject: [PATCH] ARC: Don't set CROSS_COMPILE in arch's Makefile
> > 
> > There's not much sense in doing that because if user or
> > his build-system didn't set CROSS_COMPILE we still may
> > very well make incorrect guess.
> > 
> > But as it turned out setting CROSS_COMPILE is not as harmless
> > as one may think: with recent changes that implemented automatic
> > discovery of __host__ gcc features unconditional setup of
> > CROSS_COMPILE leads to failures on execution of "make xxx_defconfig"
> > with absent cross-compiler, for more info see [1].
> > 
> > Set CROSS_COMPILE as well gets in the way if we want only to build
> > .dtb's (again with absent cross-compiler which is not really needed
> > for building .dtb's), see [2].
> > 
> > Note, we had to change LIBGCC assignment type from ":=" to "="
> > so that is is resolved on its usage, otherwise if it is resolved
> > at declaration time with missing CROSS_COMPILE we're getting this
> > error message from host GCC:
> > ------------------------->8-------------------------
> > gcc: error: unrecognized command line option ‘-mmedium-calls’
> > gcc: error: unrecognized command line option ‘-mno-sdata’; did you mean ‘-fno-stats’?
> > ------------------------->8-------------------------
> > 
> > [1] http://lists.infradead.org/pipermail/linux-snps-arc/2018-September/004308.html
> > [2] http://lists.infradead.org/pipermail/linux-snps-arc/2018-September/004320.html
> > 
> > Signed-off-by: Alexey Brodkin <abrodkin@...opsys.com>
> > Cc: Masahiro Yamada <yamada.masahiro@...ionext.com>
> > Cc: Rob Herring <robh@...nel.org>
> > ---
> >  arch/arc/Makefile | 10 +---------
> >  1 file changed, 1 insertion(+), 9 deletions(-)
> > 
> > diff --git a/arch/arc/Makefile b/arch/arc/Makefile
> > index 99cce77ab98f..5f6b67917dc2 100644
> > --- a/arch/arc/Makefile
> > +++ b/arch/arc/Makefile
> > @@ -6,14 +6,6 @@
> >  # published by the Free Software Foundation.
> >  #
> > 
> > -ifeq ($(CROSS_COMPILE),)
> > -ifndef CONFIG_CPU_BIG_ENDIAN
> > -CROSS_COMPILE := arc-linux-
> > -else
> > -CROSS_COMPILE := arceb-linux-
> > -endif
> > -endif
> > -
> >  KBUILD_DEFCONFIG := nsim_700_defconfig
> > 
> >  cflags-y	+= -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__
> > @@ -79,7 +71,7 @@ cflags-$(disable_small_data)		+= -mno-sdata -fcall-used-gp
> >  cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= -mbig-endian
> >  ldflags-$(CONFIG_CPU_BIG_ENDIAN)	+= -EB
> > 
> > -LIBGCC	:= $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
> > +LIBGCC	= $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
> > 
> >  # Modules with short calls might break for calls into builtin-kernel
> >  KBUILD_CFLAGS_MODULE	+= -mlong-calls -mno-millicode
> > --
> > 2.17.1
> 
> May we have this one back-ported to stable branches?
> 
> Upstream commit in Linus' tree is:
> 40660f1fcee8 ("ARC: build: Don't set CROSS_COMPILE in arch's Makefile").

Applied to 4.9.y, 4.14.y, and 4.18.y, thanks.

greg k-h