From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.formilux.org (mta1.formilux.org [51.159.59.229]) (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 C0F4921A457; Sun, 11 Oct 2026 17:38:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=51.159.59.229 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791740322; cv=none; b=AreTF+BvfabpRmjkfX/9zFhdYdx9iDnamNTWJPVTbwTJqTTSkpWdMab/2gz0Mp4L0VEkewDw9cgDYEVEBBxKL98wuZ6+NH0U929TIj5M6nWoY1NWgSJfZYWes5Qc0B2xnSu0twAH+vg6hND67aCXsXifQHLwwRTKsLgKp3Xf1Bk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791740322; c=relaxed/simple; bh=yO7TYUdsNEouy+r8LNXK9jTl+YP+UbRG2kou+F9S2Eo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=o72yJhDa2Rrq60jg0cOXEjm/AvQ5VUHVySwW9t8rHEYPi2JgdQJEjfuqCIypYoMRepayKDvZ/hdhxwhIWZ/V+RLJXYja/Tl0IKo4cJTEvY7V24eN7UCzpIFYLNC0NFe7nO8qGNYuYVCB5KDjkRalCAfZ2b7nkP39PM9WsGxwKs0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=1wt.eu; spf=pass smtp.mailfrom=1wt.eu; dkim=pass (1024-bit key) header.d=1wt.eu header.i=@1wt.eu header.b=lsJd3Mgp; arc=none smtp.client-ip=51.159.59.229 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=1wt.eu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=1wt.eu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=1wt.eu header.i=@1wt.eu header.b="lsJd3Mgp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1wt.eu; s=mail; t=1791740310; bh=s9SvmzBmiwivVauLGFTbFp3qv/QIUAQiXVjv0kh1bWE=; h=From:Message-ID:From; b=lsJd3MgpzqlNQwkq4cvLnFsSkXJRgiIuLDYHh+mZX6iNnyXTP0C4eRHn3suNHLVNk OpNeO/ugLo+uUkXJ6zZkXEARp78wDjvk380s4WDwQP59vZl17ZYrdCx4Hsa4xFyCFl tlEvJnUpUGPc8y3eUIGXEQb7AiMTzCOKdr8FapYM= Received: from 1wt.eu (ded1.1wt.eu [163.172.96.212]) by mta1.formilux.org (Postfix) with ESMTP id 7FD9FC0920; Sun, 11 Oct 2026 19:38:30 +0200 (CEST) Date: Sun, 11 Oct 2026 19:38:29 +0200 From: Willy Tarreau To: Sebastian Andrzej Siewior Cc: Tancred , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, "H. Peter Anvin" , "Maciej W. Rozycki" , Bill Wendling , Borislav Petkov , Dave Hansen , Ingo Molnar , John Paul Adrian Glaubitz , Jonathan Corbet , Justin Stitt , Nathan Chancellor , Neal Gompa , Nick Desaulniers , Richard Purdie , Sam James , Shuah Khan , Thomas Gleixner , Thomas =?iso-8859-1?Q?Wei=DFschuh?= , Tomas Glozar , x86@kernel.org, Arnd Bergmann Subject: Re: [PATCH v4 2/2] x86: Start removing X86_X32_ABI Message-ID: References: <20261008-x32_removal-v4-0-d389a193c506@breakpoint.cc> <20261008-x32_removal-v4-2-d389a193c506@breakpoint.cc> <7f315c7a-0fd1-4f7e-93bb-703d4107aa5a@narraduct.com> <20261011171946.gMv8V9Ck@breakpoint.cc> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261011171946.gMv8V9Ck@breakpoint.cc> On Sun, Oct 11, 2026 at 07:19:46PM +0200, Sebastian Andrzej Siewior wrote: > On 2026-10-09 20:13:55 [-0600], Tancred wrote: > > > > > > On 10/8/26 03:07, Sebastian Andrzej Siewior wrote: > > > where certain workloads widely > > > move to x32 and use it exclusively. In the meantime Debian introduced a > > > patch to disable x32 by default (so it has to be enabled at boot time on > > > the command line) because they are afraid of the increased attack > > > surface. Fedora as far as I tell has X32 disabled (looking at 7.0-rc5 > > > rpm in rawhide). > > > > > > Since there is practically no real use for x32 > > > > I only recently discovered x32 and built a Desktop (with all daemons and > > utilities running 10-30% smaller and some a bit faster, with 64 bit > > libraries for eg. Firefox.) My experiment should definitely not decide > > anything, but how much real-world use would be sufficient to justify > > continued presence (more complex compat code)? > > "a bit faster" needs actual numbers to justify. One examples was quicker > gcc but I don't see a x32 compile farm leveraging this benefit. FWIW I do build my ARM cross-compilers in a32 because they're generally ~10-15% faster than in a64. I wouldn't be surprised if that was the same on x86 because tools such as compilers very likely use pointers a lot. In a build farm it certainly makes a difference, possibly not sufficient to justify keeping a kernel port, but it's just to illustrate one valid use case. Willy