From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 B5E6430FF1D for ; Tue, 7 Jul 2026 21:22:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783459377; cv=none; b=vDwiNG/CrFubSkG8cjPmIRyWllHUi9VFYWniMiA/FeyPZcGkJUlsbNH+FSF2cdCK3D2zFw6Q5Kbd1lFeVPObnIyPxVUfDMPFKSJ6SGnhfEa7rDBWZD5Pmpwp2dNREQMbVbSRSwbRVfnDXWAslJLvIdP9+fdB1Dxz7yMdp/h0CkA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783459377; c=relaxed/simple; bh=Rfyidm19Eo+AP2eduQbr8VE3W32OTmTl5LoiuiLLIis=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=FtlcEal/mIsC1D+g0dsKYpCv48UTciqlAEL5qFNb63acnGtiECtn/Z76TcbSYIMCW2oDFM41AylJp2pGbomWqSCz3A47+qDBihDgLmyM5ErRd95YYvwlgUXpIlWW3pAk44BGTay5sbLVkNxB+1SnbOJgZ1xF8S3evgfwziyZlLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=ANhm/r4s; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=0gZA34w7; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="ANhm/r4s"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="0gZA34w7" Date: Tue, 7 Jul 2026 23:22:52 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1783459374; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=xarwOBKr3rIul2vyFIn5LXa10ru3oR4n7ZipREoKSdE=; b=ANhm/r4sBMLEkxvvse9w8hPicPlDY6T/7WiA2U2z9U/j85gk7RnVpsE/mmFFNSkGIa5Pch a9LmoRxu53saj3KwN6nX+acbUmZopmZWFSeDx6n5QU+DL3zMqWJcvyGq8gGZu0HtRzcLTZ GyhSvS0uPtmXvDza1ubN0u7OPMvKoYXlrkiK4Bz8cuDmf8FsAyhZnk4B7pEI0mV9MEGX+m /z6VLnM31Oq4OKdvIPPbLxVUHDtLt8fup19K2mnRjumXi7r99socYeFjj3ZuQ1A/4mShcP 63ePEiIbMP+AoJQbaFcXa46jxYV3/zQIFq5eq0/2AXuGHl2JVysudsv8Z5loyA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1783459374; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=xarwOBKr3rIul2vyFIn5LXa10ru3oR4n7ZipREoKSdE=; b=0gZA34w7SD1P1vwWDxTlU18PEP7mAPHOPN81kI1KoMCln1YNrbWcZbk6tRlJV0w02q8cF5 9+KOnsy1+pZrgbBA== From: Sebastian Andrzej Siewior To: 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 , John Paul Adrian Glaubitz , Tomas Glozar , "Maciej W. Rozycki" , Richard Purdie Subject: [PATCH v2] x86: Start removing X86_X32_ABI Message-ID: <20260707212252.bYk3-AlU@linutronix.de> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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. 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). 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. 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. Signed-off-by: Sebastian Andrzej Siewior --- v1=E2=80=A6v2: https://lore.kernel.org/r/20260523093734.A3AR7reJ@linutronix= =2Ede - reword commit description, don't claim the syscall range can be used. arch/x86/Kconfig | 14 -------------- 1 file changed, 14 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index bdad90f210e4b..f6fe55fdc928a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -3097,20 +3097,6 @@ config IA32_EMULATION_DEFAULT_DISABLED processes and access to 32-bit syscalls. If unsure, leave it to its default value. =20 -config X86_X32_ABI - bool "x32 ABI for 64-bit mode" - depends on X86_64 - # llvm-objcopy does not convert x86_64 .note.gnu.property or - # compressed debug sections to x86_x32 properly: - # https://github.com/ClangBuiltLinux/linux/issues/514 - # https://github.com/ClangBuiltLinux/linux/issues/1141 - depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) - help - Include code to run binaries for the x32 native 32-bit ABI - for 64-bit processors. An x32 process gets access to the - full 64-bit register file and wide data path while leaving - pointers at 32 bits for smaller memory footprint. - config COMPAT_32 def_bool y depends on IA32_EMULATION || X86_32 --=20 2.53.0