From mboxrd@z Thu Jan 1 00:00:00 1970 From: "George Spelvin" Subject: Re: [RFC PATCH 2/2] arch/m68k: Add CONFIG_CPU_HAS_NO_MULDIV32 Date: 12 May 2016 22:39:32 -0400 Message-ID: <20160513023932.16877.qmail@ns.horizon.com> References: Return-path: Received: from ns.horizon.com ([71.41.210.147]:57096 "HELO ns.horizon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752216AbcEMCje (ORCPT ); Thu, 12 May 2016 22:39:34 -0400 In-Reply-To: Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: fthain@telegraphics.com.au, linux@horizon.com Cc: geert@linux-m68k.org, gerg@linux-m68k.org, linux-m68k@lists.linux-m68k.org Finn Thain wrote: > On Fri, 12 May 2016, George Spelvin wrote: >> +# Old GCC versions fall back to -m5200 compilation, generating these calls >> +# even though the CPU doesn't actually need it. See arch/m68k/Makefile. > > The comment is vague. Does anyone know which GCC versions do or don't work > like this? Yes, I looked it up in the archived GCC documentation. My current patch says: (commit comment) Since the compiler version is not known at Kconfig time, this cannot be expressed in a CONFIG_ variable, but instead is handled by some Makefile hackery. This only applies to GCC 4.2.4 and earlier, which is hopefully almost everyone, but Documentation/Changes says GCC 3.2. (arch/m68k/lib/Makefile) +# GCC 4.2.4 and earlier don't know about ColdFire models that support +# DIV.L and fall back to -m5200, generating these calls even though the +# CPU doesn't actually need it. Not needed on GCC 4.3 or later. +# See the $(call cc-option ...) lines in arch/m68k/Makefile.