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 27CB43C37B4 for ; Wed, 8 Jul 2026 06:31:37 +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=1783492300; cv=none; b=uiKNrZ9Qj6rZ7wK6SLwdgYhQsRZ4SLwgNSw0zBVshHBlprHpsr21BPe/LBkDasyZQL4Zphqgif4Sa3pfj00RIC9e+H6UeEmOAFhiYuzuIEm4qsyJRzbkliZYTJJVMCu5f0epsftyMpCe68YPgMtPgi68n9Zx+uq9dAMyn4CrvD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783492300; c=relaxed/simple; bh=v/Xm3xyOqi/cv/p3ULlb23oH64Rz/AGXAVRlA01ilNo=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=B+XZoaFlMecyIXo0Eld1OQRh+6BfdqJW6VatSR8Ptb9ydaAhLrkjGgBbIrHNX4ApFEn2s2CURX8+mKicGVnJ9hN6JcuQZGao1NKujsJr0y1aB9yTdXAmEIgdJ4Rt7WFgETFwd//Tx8vw9CWEu3n6Rv0eqbRkbHqOjp5UjbSzACo= 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=fGIVgWbH; 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="fGIVgWbH" 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=FcjA6Um9Lq/NpMyjgySS+nkoxE4AQFJx0YkORNAKkU0=; t=1783492297; x=1784097097; b=fGIVgWbH25ljfTNdyhMxwPgJwizsNEE3A/vz1+WGwez/XP2rzWC+WCLYj3VFD P9hyudi09ROcDvtFAQQJjc3dBzd25pbK6W9C5magJeTCtIAaj3VLWyMZy2GXVu7ekfewQ6EQNxeKJ ATR3G8oMZse4O0gsK3A0GUSGC3FZlS1dwv4zHbIjNJr+FD/PeXKBThIU64DLv9ofsowaGg77x0XiN TSRZLfq3eqUfwa2sDJnU+H1SyJNprOpslqDOMxTS+cXWAqAWiSVYpGzy6j/N5UuLWVUuz5+Dk0hmx Y5vflXXDK/xueUg1PGdbj4egAZRpQgtkJaw46X/UPg+az7QthA==; 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 1whLoi-00000000Bj4-10dI; Wed, 08 Jul 2026 08:31:32 +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 1whLoh-00000003SjW-419y; Wed, 08 Jul 2026 08:31:32 +0200 Message-ID: Subject: Re: [PATCH v2] 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 , Arnd Bergmann , Sam James , Neal Gompa , Tomas Glozar , "Maciej W. Rozycki" , Richard Purdie Date: Wed, 08 Jul 2026 08:31:30 +0200 In-Reply-To: <20260707212252.bYk3-AlU@linutronix.de> References: <20260707212252.bYk3-AlU@linutronix.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 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, On Tue, 2026-07-07 at 23:22 +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 syscall range >512 used by x32 can not be reused because on earlier > kernels (before v5.4 with x32 enabled, see commit 6365b842aae4 > ("x86/syscalls: Split the x32 syscalls into their own table") it is not > obvious if the syscall is for x86-64 and not implemented or meant for > x32. > What can be removed are the special compat cases due to different > alignment. >=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 by the end of the year, it will removed after the last LTS > kernel this year. As mentioned before, there are still actively maintained Debian and Gentoo ports of x32, so I guess the last paragraph is rather subjective. Adrian --=20 .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913