From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outpost1.zedat.fu-berlin.de (outpost1.zedat.fu-berlin.de [130.133.4.66]) (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 9676F1F91E3 for ; Wed, 27 May 2026 15:57:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=130.133.4.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779897459; cv=none; b=rzJzH6Xqjb5z0CaSmSHOyYNv9/Nz8hyEeeQYdG6GvaSzGnNmi80ZlwQpV9XlDYXAgbQT1HF7dhBIsRqTw9avxApResNSF4T31EJNN6Cab3w93t8A7/EakQg0REK0rjvQ4S1ws7bhLajW930pItTi7ZlpIcdGxDw0sEQgA1k7GIs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779897459; c=relaxed/simple; bh=c54b0qeTRvB15hO5J3wjbYbvyRXCVWXPet6xaNyN5dk=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=V1T73iHP8vwk86H/G1Q43/eptpq1riDKOaiYnp9OhvAhIIcduVDDa4JMpK3bjAjXSqwUuifWIrVQ9/x28cPROXl50bhUBHGb5NU9gXnwYaZhaDmYaC21oScioD3A1hQuBgk/NX/9jbrfhEPZpGbnur8Eh9CRLdvqfmWq5Ih5X84= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=physik.fu-berlin.de; spf=pass smtp.mailfrom=zedat.fu-berlin.de; dkim=pass (2048-bit key) header.d=fu-berlin.de header.i=@fu-berlin.de header.b=Ypv08jYa; arc=none smtp.client-ip=130.133.4.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=physik.fu-berlin.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zedat.fu-berlin.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fu-berlin.de header.i=@fu-berlin.de header.b="Ypv08jYa" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=fu-berlin.de; s=fub01; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:From: Reply-To:Subject:Date:Message-ID:To:Cc:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:In-Reply-To: References; bh=lpxdlxxZ45u+YzCSXXJ+eKwHfohZj0h5BAHwR2c/TaY=; t=1779897455; x=1780502255; b=Ypv08jYa4YWtVLI04Uycf8VGPfSzQvFQOeXjRICjY2fMSGff/hlJFgokxyeLL ANEe9+5ZtpFAd0wkVqLQ+9uXAQkFuOOuJn7tBstS+UxMnXixrO9g04iVJXqyzGYlvh9ME/0+68Inn ki1lrnQRcPHt3zcd1VHuvEkyBK3FpWNQKZDLsLN9EwRG13c1GpYkQ36iopbx/75qC4CUQb7+H+XVc yr3Hclb7Sgmj6GmJgEwdgFCDwuZURnnJl1jeH9tdHWh1RxbUkNRl2bG7gki1DV5Wln90/K6KiibrG 134qEZI9LZWi+xfW5XLUP8d6Aie+Ijf1fYKCgp3TLehGEHw87w==; Received: from inpost2.zedat.fu-berlin.de ([130.133.4.69]) by outpost.zedat.fu-berlin.de (Exim 4.99) with esmtps (TLS1.3) tls TLS_AES_256_GCM_SHA384 (envelope-from ) id 1wSGdP-00000000Gr9-1rw2; Wed, 27 May 2026 17:57:31 +0200 Received: from p57bd94c1.dip0.t-ipconnect.de ([87.189.148.193] helo=[192.168.178.61]) by inpost2.zedat.fu-berlin.de (Exim 4.99) with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (envelope-from ) id 1wSGdP-000000013Gs-0sEy; Wed, 27 May 2026 17:57:31 +0200 Message-ID: Subject: Re: [PATCH] x86: Start removing X86_X32_ABI From: John Paul Adrian Glaubitz To: Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, x86@kernel.org Cc: "H. Peter Anvin" , Borislav Petkov , Dave Hansen , Ingo Molnar , Jonathan Corbet , Thomas Gleixner Date: Wed, 27 May 2026 17:57:30 +0200 In-Reply-To: <20260523093734.A3AR7reJ@linutronix.de> References: <20260523093734.A3AR7reJ@linutronix.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Original-Sender: glaubitz@physik.fu-berlin.de X-ZEDAT-Hint: PO Hello Sebastian, On Sat, 2026-05-23 at 11:37 +0200, Sebastian Andrzej Siewior wrote: > The x32 ABI was introduced in v3.4 to leverage the additional registers > which were available on x86_64 but not on i386 while keeping the smaller > 32bit pointers. >=20 > This did not take off. The memory usage usually knows no limit and the > better performance did not reach a point 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). >=20 > The last syscall for x86_64 is currently at 471. The first x32 starts at > 512 which leaves 40 new syscalls in between. Without the x32 ABI, those > syscalls could be used since x32 wouldn't be an option and therefore > reserved. >=20 > Since there is practically no real use for x32, start removing it by > removing the symbol first, not allowing to enable it. Should nothing > happening within the next half year, lets remove code bits around August > after the summer break. Debian still has an x32 port which is building unstable packages, see [1]. Even Rust works there. Adrian > [1] https://buildd.debian.org/status/architecture.php?a=3Dx32&suite=3Dsid --=20 .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913