From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Tue, 13 Apr 2004 22:48:09 +0000 Subject: Re: proposed gcc/gas -mb-step changes Message-Id: <16508.28201.916283.528284@napali.hpl.hp.com> List-Id: References: <1081840653.1046.64.camel@leaf.tuliptree.org> In-Reply-To: <1081840653.1046.64.camel@leaf.tuliptree.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On 13 Apr 2004 00:17:32 -0700, Jim Wilson said: Jim> Zack Weinberg of CodeSourcery sent mail to the binutils mailing Jim> list which proposes to add a new -mb-step option to the Jim> assembler. Currently, gas will always give warnings if given Jim> code which triggers an Itanium (Merced) B-step errata. The Jim> proposal is to only warn when the new -mb-step option is used. Jim> Also, this means that the existing gcc option -mb-step will Jim> have to pass -mb-step to the assembler. The discussion is here Jim> http://sources.redhat.com/ml/binutils/2004-04/msg00187.html Jim> The linux kernel is the only code I know of that uses the gcc Jim> -mb-step option. This is used if you configure with B-step Jim> support enabled. This change means that the kernel should be Jim> modified to add -mb-step to aflags when the B-step support is Jim> enabled, just like it currently does for cflags. Gas will fail Jim> if given a -m option it doesn't recognize, so this means that Jim> these changes will only work with new assembler versions. I am Jim> assuming that use of the B-step support is rare enough that Jim> this won't be a problem. Seems like an acceptable solution to me. IIRC, the Errata being worked around by -mb-step was exceedingly rare to trigger and I'm not even sure it was ever observed to trigger in a realworld situation. If so, perhaps it would be OK to drop -mb-step entirely. That would cause a small risk for users of B-step Itanium (Merced) CPUs, but I can't imagine anyone is doing anything "mission-critical" on prototype machines anyhow. For testing etc., the a kernel compiled without -mb-step should still be usable, AFAIK. --david