linux-kernel - Re: X86 GIT GCC 5 compilation warning

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Message-ID: <20150615171750.GP4255@pd.tnic>
Date:	Mon, 15 Jun 2015 19:17:50 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Michael Matz <matz@...e.de>
Cc:	Enrico Mioso <mrkiko.rs@...il.com>, linux-kernel@...r.kernel.org,
	x86-ml <x86@...nel.org>
Subject: Re: X86 GIT GCC 5 compilation warning

On Mon, Jun 15, 2015 at 01:30:11PM +0200, Michael Matz wrote:
> This warning is in gas since 2009 (commit d85733c8). In this case
> it only happens when the internal type to represent values is 32
> bit, which happens only when binutils is compiled for only non-64bit
> architectures, _on_ a non-64bit architecture (e.g. when it's compiled
> on i386 for i386).

Hmm, so I did start my oS13.2 i386 guest:

$ as --version
GNU assembler (GNU Binutils; openSUSE 13.2) 2.24.0.20140403-6.1
Copyright 2013 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or later.
This program has absolutely no warranty.
This assembler was configured for a target of `i586-suse-linux'.

So this target is "i586-suse-linux" and you said
"i386-unknown-linux-gnu". Could that be a difference?

$ gcc --version
gcc (SUSE Linux) 4.8.3 20140627 [gcc-4_8-branch revision 212064]
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ file /usr/bin/as
/usr/bin/as: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 3.0.0, BuildID[sha1]=92485c2176310e60e8c833b6a0a8d9f8b8e9aea2, stripped

$ make arch/x86/kernel/head_32.o
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/bounds.h
  CHK     include/generated/asm-offsets.h
  CALL    scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  CC      kernel/time/time.o
  AS      arch/x86/kernel/head_32.o
  CHK     kernel/config_data.h
  LD      kernel/time/built-in.o
  LD      kernel/built-in.o

No warnings.

If I do a separate .s test dummy, it doesn't bitch either:

$ cat t.s
.text
LOWMEM_PAGES = (((1<<32) - 0xc0000000) >> 12)

        mov LOWMEM_PAGES, %eax

$ as t.s
$

Do we have some bleeding edge gcc5 rpms somewhere I could try?

Thanks Micha.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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