From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fhigh-b7-smtp.messagingengine.com (fhigh-b7-smtp.messagingengine.com [202.12.124.158]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ADBC817BD3 for ; Thu, 19 Jun 2025 05:31:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.12.124.158 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750311074; cv=none; b=ahm1A6aF0ZrwnAIY+OZY1SHAsThgU41/WIYmlVm+8nIBWL2KboZDEXz7JMU6IUMIEwouWjwS/9+vm370uKj+y+GYEm28rRsB8MIYPcAwVjJMeMHsYsizBSoV+G2R2OWeE04JlphIUasphLQgXs+MD+Ffu//7vZANUPRilO3Y+IE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750311074; c=relaxed/simple; bh=brBkX254+HtFTbIDmXArbVz9BZB1IXWYqwtLIA0mk9k=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=bF0oZt4oqUlcw+6jvbos1K71cLu4yV8pk2GuF7TbGi4cB2u5pMuYquXYGfSXorjdiIxF+ZQOEUzALl+OPXuY8StGn3bguz0t8ljIXFlI1xDLcyZ6zMmixy8d2uyFJQZ3EUuHVEy0s0RSki7sQEMqwdURhAHfUoeWa7ARjjtphcY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org; spf=none smtp.mailfrom=linux-m68k.org; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=NGwlZ2fv; arc=none smtp.client-ip=202.12.124.158 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux-m68k.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="NGwlZ2fv" Received: from phl-compute-04.internal (phl-compute-04.phl.internal [10.202.2.44]) by mailfhigh.stl.internal (Postfix) with ESMTP id 201912540061; Thu, 19 Jun 2025 01:31:10 -0400 (EDT) Received: from phl-mailfrontend-02 ([10.202.2.163]) by phl-compute-04.internal (MEProxy); Thu, 19 Jun 2025 01:31:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; t= 1750311069; x=1750397469; bh=yxDfoETC+JWjepeeILNMDxvSyAHhiAMHTIh PHAZraZ0=; b=NGwlZ2fvpwQE7tUWkhlPAawWi5O/b79K1NCecVOh3bT1svaeY5T QkcalfmOmed54WcYtJUit82q2gnveQUG5lshdcw1nKqfhgLn6yM7sUdSTgMpw1a4 Bwmn187jVagUdyrCOhAsCQd5gWfWw/ZBYjT+5Ly43eYlRHbu1eo+jSp5qhK1aZCW Eo0adjNvHb25VZ2PnsZvc11jXy0T9Ly7/u9D3p0Ob3FbouUcbd63cxYkuaP5UDK0 Ejh17ZJPdrQA8tUGYQsEjmlNyfu+FV65mS/kpc+gnmKnSjwsUTv+PU8xrTcywRYY p4dRmv2968/jFZvdIqtcetVa5bmN702t3OQ== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtddvgdegieelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceurghi lhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurh epfffhvfevufgjkfhfgggtsehttdertddttddvnecuhfhrohhmpefhihhnnhcuvfhhrghi nhcuoehfthhhrghinheslhhinhhugidqmheikehkrdhorhhgqeenucggtffrrghtthgvrh hnpeelueehleehkefgueevtdevteejkefhffekfeffffdtgfejveekgeefvdeuheeuleen ucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehfthhhrg hinheslhhinhhugidqmheikehkrdhorhhgpdhnsggprhgtphhtthhopeeipdhmohguvgep shhmthhpohhuthdprhgtphhtthhopehgvghrgheskhgvrhhnvghlrdhorhhgpdhrtghpth htohepghhlrghusghithiisehphhihshhikhdrfhhuqdgsvghrlhhinhdruggvpdhrtghp thhtohepghgvvghrtheslhhinhhugidqmheikehkrdhorhhgpdhrtghpthhtohepphhorh htqdhmieekkhesnhgvthgsshgurdhorhhgpdhrtghpthhtohepuggvsghirghnqdeikehk sehlihhsthhsrdguvggsihgrnhdrohhrghdprhgtphhtthhopehlihhnuhigqdhmieekkh esvhhgvghrrdhkvghrnhgvlhdrohhrgh X-ME-Proxy: Feedback-ID: i58a146ae:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 19 Jun 2025 01:31:06 -0400 (EDT) Date: Thu, 19 Jun 2025 15:31:58 +1000 (AEST) From: Finn Thain To: Greg Ungerer cc: John Paul Adrian Glaubitz , Geert Uytterhoeven , port-m68k , debian-68k , linux-m68k Subject: Re: Question on BIGGEST_ALIGNMENT in GCC on NetBSD/m68k In-Reply-To: Message-ID: <931c08f8-1d1c-a317-5380-aa41b26bfed4@linux-m68k.org> References: <5d8619dfe4134319b558684209f2b89c5c1447cf.camel@physik.fu-berlin.de> <889f54af-2317-ee51-cea5-47d813683944@linux-m68k.org> <5de0835e46f8c2479668fe5fe98f8e0d230cbfce.camel@physik.fu-berlin.de> <0b09dcea10c9bab4a50b2599ef8ac59b89f09b3e.camel@physik.fu-berlin.de> <8eb87c55-95c2-0c73-4941-6e8732266220@linux-m68k.org> <4c0581c5baccf73e96e53d755e70b57b23ba1da4.camel@physik.fu-berlin.de> <29677f1e81b42c87926875109907485e41587883.camel@physik.fu-berlin.de> <38c670cc-6169-4720-a883-c34df26e1a4f@kernel.org> Precedence: bulk X-Mailing-List: linux-m68k@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii On Thu, 19 Jun 2025, Greg Ungerer wrote: > On 19/6/25 08:29, Finn Thain wrote: > > > On Wed, 18 Jun 2025, Greg Ungerer wrote: > > > >>> It's not really necessary to enforce this on Coldfire. However, > >>> since buildroot builds completely from source, it wouldn't even be a > >>> problem to change the alignment there as well. > >> > >> Yes, that is totally right in my experience. Certainly in my ColdFire > >> work it is pretty much always a build-everything approach via > >> buildroot or similar. I wouldn't think an ABI change would actually > >> worry too many ColdFire uses, they don't use distributions like > >> debian on them. (I would love to hear from anyone who does!). > >> > > > > That may work for end-users with a vendor BSP. But upstream developers > > need to be able to swap components. In general, when debugging I often > > have to run old binaries to find out whether I'm dealing with a deeper > > regression or not. Also, there is the bisection problem. It's not just > > a couple of distros who get to pay for an ABI break. It's the entire > > ecosystem. > > I am sure there is value in that for some. Like I said though that has > not been my experience with ColdFire. And by that I mean as the upstream > maintainer of ColdFire Linux support for +20 years. I pretty mush > _always_ build kernel + libs + user for testing even small kernel > changes. OK, so you're not building binutils, newlib, gcc, gdb etc. with each revision. Do you use a board support package (BSP) from the vendor? > My standard small system build takes less than 1 minute for everything. > Again, I am just relating my experience with this - admittedly probably > not typical of actual end users. > > FWIW even when I was working on shipping ColdFire based products my > firmware was always a complete update, no separate kernel and user space > updates. Typical of small embedded systems. I can't actually remember > many times I have run with a previously compiled user space. > Given that on-chip RAM is scarce on Coldfire devices, it seems entirely plausible that an alignment change could result in ENOMEM after a rebuild -- unless the toolchain offered a choice of ABI. So this becomes a burden for those who maintain tooling that deals with ABIs, as well as for the vendor which has to support its BSP -- unless the vendor also happens to desire a choice of alignment (that's why I raised that question on 6/6).