linux-kernel - Re: [kbuild-all] mipsel-linux-gnu-gcc: error: unrecognized command line option '-mcompact-branches=optimal'

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Message-ID: <20160421203415.GK24051@linux-mips.org>
Date:	Thu, 21 Apr 2016 22:34:15 +0200
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	"Maciej W. Rozycki" <macro@...tec.com>
Cc:	Fengguang Wu <fengguang.wu@...el.com>, kbuild-all@...org,
	Paul Burton <paul.burton@...tec.com>,
	linux-kernel@...r.kernel.org, Philip Li <philip.li@...el.com>
Subject: Re: [kbuild-all] mipsel-linux-gnu-gcc: error: unrecognized command
 line option '-mcompact-branches=optimal'

On Thu, Apr 21, 2016 at 08:55:34PM +0100, Maciej W. Rozycki wrote:

> > % mips-linux-gnu-gcc --version
> > mips-linux-gnu-gcc (Debian 5.2.1-16) 5.2.1 20150903
> > Copyright (C) 2015 Free Software Foundation, Inc.
> > 
> > How about temporarily disable that error, until we upgrade to a new
> > gcc version which supports the -mcompact-branches option?
> 
>  I don't think it makes sense as the compiler won't support MIPSr6 code 
> anyway, so first it'll bail out on `-march=mips32r6', and if we go even 
> further and disable that too, then GAS will probably break somewhere on 
> inline asm and GCC will produce code which does not make sense otherwise.

GCC 5.2.0 claims to support mips32r6 and mips64r6.  It's just the option
-mcompact-branches which seem to have been added later only.

  Ralf