From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from terminus.zytor.com (terminus.zytor.com [198.137.202.136]) (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 8496E29B766; Thu, 8 Oct 2026 12:19:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791461942; cv=none; b=PocYeHM/1MwAxH8TGn4tFLrpqyN/kS2SoB+kzZGoMWR88FaLWf7bgFIL7C+N1K9FnfPFSn+RGKt95xCv370QI4Gc1ii3sdFqgaV8+4Zo5ZbIAf58oOqZq+AtixTpwVRvUv8pZNAw++Fpx22ZVdJLmFoDMfkHknCtZ5b3MHhhQi4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791461942; c=relaxed/simple; bh=5PuCP3CbXgI2IH2YwCi71AGOGwZE3Xt70lyE94ahk3c=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=av71F5Fz2sckRbwvyupRJud3svt8rHE9ALj2pgvAl3d9w6fiKZMHuCq2MVII6pyBeaAVlHTLSq5mAsaRUIPWeKS2WhJcibPcf+nKwjOLQgLyGHyWoYTm/BZoyJaJIZW3AbTqvATrI1IFSI/6QFbClRbtRrizs2/npPmgaPLt38k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=ZW8cEflJ; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="ZW8cEflJ" Received: from ehlo.thunderbird.net ([172.59.192.127]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 698CFmc62830241 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Thu, 8 Oct 2026 05:15:50 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 698CFmc62830241 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2026092801; t=1791461752; bh=vg1ZKcmZSmYiLGnDiNyOm2ayv4LK+74uEkyw4KKmmPM=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=ZW8cEflJDXVXYnpyK9H5g3k4nuGp0DuSVeP2bAHqAqHjxCMGXfCYZD6wDBams6Nty E4Yz5ggCffOp+Wa6x4wIXrJ1RNOkqLLi/eqj2NyhDPgWHJKO4hsZpShfNNGuvP4tRt lCrDA0UQ8vCzAc9IANdoS8iWZ+2OPTV+9dVWeR44Zx1HYFNqwq+W3DLmsPyxxuZolr gdUFcuOofFrvHUIG7O6pL1jKmoJHw31xe7UPUZtq6r74EpxaYn5WznJatDlWXKL709 cSkg8vJWdDOLkd2zjZWabYAE/T0sNiHEZy0SfznUmAMRy4ztmJsdwchf0SboC0NLAZ xrY/FIIF5+fmA== Date: Thu, 08 Oct 2026 14:15:39 +0200 From: "H. Peter Anvin" To: Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org CC: Sebastian Andrzej Siewior , "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 , =?ISO-8859-1?Q?Thomas_Wei=DFschuh?= , Tomas Glozar , Willy Tarreau , x86@kernel.org, Arnd Bergmann Subject: Re: [PATCH v4 2/2] x86: Start removing X86_X32_ABI User-Agent: K-9 Mail for Android In-Reply-To: <20261008-x32_removal-v4-2-d389a193c506@breakpoint.cc> References: <20261008-x32_removal-v4-0-d389a193c506@breakpoint.cc> <20261008-x32_removal-v4-2-d389a193c506@breakpoint.cc> Message-ID: <2B66CB7E-2302-470F-A3B5-0566DCF2A826@zytor.com> 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-Transfer-Encoding: quoted-printable On October 8, 2026 11:07:43 AM GMT+02:00, Sebastian Andrzej Siewior wrote: >From: Sebastian Andrzej Siewior > >From: Sebastian Andrzej Siewior > >The x32 ABI was introduced in v3=2E4 to leverage the additional registers >which were available on x86_64 but not on i386 while keeping the smaller >32bit pointers=2E > >This did not take off=2E 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=2E 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=2E Fedora as far as I tell has X32 disabled (looking at 7=2E0-rc5 >rpm in rawhide)=2E > >The syscall range >512 used by x32 can not be reused because on earlier >kernels (before v5=2E4 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=2E >What can be removed are the special compat cases due to different >alignment=2E > >Since there is practically no real use for x32, start removing it by >marking the symbol as BROKEN so it is not possible to enable by default= =2E >It will remain around in the last LTS kernel of this year and then it >will be removed=2E > >Acked-by: Arnd Bergmann >Signed-off-by: Sebastian Andrzej Siewior >--- > arch/x86/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > >diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >index 15fd9ec5ecacb=2E=2E21a6863e14e7a 100644 >--- a/arch/x86/Kconfig >+++ b/arch/x86/Kconfig >@@ -3104,7 +3104,7 @@ config IA32_EMULATION_DEFAULT_DISABLED >=20 > config X86_X32_ABI > bool "x32 ABI for 64-bit mode" >- depends on X86_64 >+ depends on X86_64 && BROKEN > # llvm-objcopy does not convert x86_64 =2Enote=2Egnu=2Eproperty or > # compressed debug sections to x86_x32 properly: > # https://github=2Ecom/ClangBuiltLinux/linux/issues/514 > Acked-by: H=2E Peter Anvin (Rosaic)