On Fri, Jul 22, 2016 at 10:08 PM, Stephen Rothwell [off-list ref] wrote:

Hi Arnaldo,

On Fri, 22 Jul 2016 16:57:34 -0300 Arnaldo Carvalho de Melo [off-list ref] wrote:

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Em Fri, Jul 22, 2016 at 02:44:17PM -0500, Josh Poimboeuf escreveu:

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On Fri, Jul 22, 2016 at 04:36:55PM -0300, Arnaldo Carvalho de Melo wrote:

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Em Fri, Jul 22, 2016 at 02:19:20PM -0500, Josh Poimboeuf escreveu:

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On Fri, Jul 22, 2016 at 11:37:39AM -0300, Arnaldo Carvalho de Melo wrote:

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I.e. with the two patches I mentioned, that are equivalent to the last patch I
sent to Stephen for testing, we would end up with HOSTARCH=powerpc and
ARCH=x86, no?

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Thanks for spelling it out, that helped a lot.

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Glad you liked it, I had to do it for my own sanity :-)

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And something that gave me mixed feelings was an e-mail from the kbuild
test bot that noticed my perf/core changes and said that the build was
broken for "make ARCH=x86_64", so I had to reinstate this part:

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ifeq ($(ARCH),x86_64)
ARCH := x86
endif

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Because, as you say, 'make ARCH=x86' works :-\ I think it will not be
needed with your patch, right? I'm checking your patch below right now,

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Yeah, that shouldn't be needed with my patch.  I think either would
work, but my patch is more of a permanent solution.

Sure, I left it there because then we don't have bisection broke at that
fix I made, i.e. 'make ARCH=x86_64' works at that point too.

I applied your patch and will push it to Ingo, now we must cross our
fingers so that Stephen doesn't come back to us once more telling it is
still broken :o)

Unfortunately, this is what I get when I just build perf/core:

  DESCEND  objtool
  CC       /home/sfr/next/x86_64_allmodconfig/tools/objtool/builtin-check.o
  LD       /home/sfr/next/x86_64_allmodconfig/tools/objtool/objtool-in.o
Warning: objtool: x86 instruction decoder differs from kernel
  LINK     /home/sfr/next/x86_64_allmodconfig/tools/objtool/objtool
In file included from /home/sfr/next/next/arch/x86/include/uapi/asm/bitsperlong.h:10:0,
                 from /home/sfr/next/next/include/uapi/asm-generic/int-ll64.h:11,
                 from /home/sfr/next/next/include/uapi/asm-generic/types.h:6,
                 from /home/sfr/next/next/arch/x86/include/uapi/asm/types.h:4,
                 from /home/sfr/next/next/tools/include/linux/types.h:9,
                 from /home/sfr/next/next/include/uapi/linux/elf.h:4,
                 from /home/sfr/next/next/arch/x86/entry/vdso/vdso2c.c:66:
/home/sfr/next/next/tools/include/asm-generic/bitsperlong.h:13:2: error: #error Inconsistent word size. Check asm/bitsperlong.h
 #error Inconsistent word size. Check asm/bitsperlong.h
  ^

The be clear: this is a ppc64le hosted, x86_64 target cross build.

I than added the following patch, and the build finishes successfully.

From: Stephen Rothwell <redacted>
Date: Sat, 23 Jul 2016 14:35:40 +1000
Subject: [PATCH] x86: make the vdso2c compiler use the host architecture
 headers

Aha, I missed that bit in the makefile.

Acked-by: Andy Lutomirski <luto@kernel.org>

-- 
Andy Lutomirski
AMA Capital Management, LLC