From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AAD27C433FE for ; Thu, 24 Feb 2022 17:34:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232011AbiBXRea (ORCPT ); Thu, 24 Feb 2022 12:34:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230322AbiBXRe2 (ORCPT ); Thu, 24 Feb 2022 12:34:28 -0500 Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DC67324FA34; Thu, 24 Feb 2022 09:33:58 -0800 (PST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 21OHTnZm019553; Thu, 24 Feb 2022 11:29:49 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 21OHTmdO019552; Thu, 24 Feb 2022 11:29:48 -0600 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Thu, 24 Feb 2022 11:29:48 -0600 From: Segher Boessenkool To: Nicholas Piggin Cc: Arnd Bergmann , linuxppc-dev , Anders Roxell , Linux Kernel Mailing List , "# 3.4.x" Subject: Re: [PATCH 2/3] powerpc: fix build errors Message-ID: <20220224172948.GN614@gate.crashing.org> References: <20220223135820.2252470-1-anders.roxell@linaro.org> <20220223135820.2252470-2-anders.roxell@linaro.org> <1645670923.t0z533n7uu.astroid@bobo.none> <1645678884.dsm10mudmp.astroid@bobo.none> <1645694174.z03tip9set.astroid@bobo.none> <1645700767.qxyu8a9wl9.astroid@bobo.none> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1645700767.qxyu8a9wl9.astroid@bobo.none> User-Agent: Mutt/1.4.2.3i Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 24, 2022 at 09:13:25PM +1000, Nicholas Piggin wrote: > Excerpts from Arnd Bergmann's message of February 24, 2022 8:20 pm: > > Again, there should be a minimum number of those .machine directives > > in inline asm as well, which tends to work out fine as long as the > > entire kernel is built with the correct -march= option for the minimum > > supported CPU, and stays away from inline asm that requires a higher > > CPU level. > > There's really no advantage to them, and they're ugly and annoying > and if we applied the concept consistently for all asm they would grow > to a very large number. The advantage is that you get machine code that *works*. There are quite a few mnemonics that translate to different instructions with different machine options! We like to get the intended instructions instead of something that depends on what assembler options the user has passed behind our backs. > The idea they'll give you good static checking just doesn't really > pan out. That never was a goal of this at all. -many was very problematical for GCC itself. We no longer use it. Segher