From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 55B7A3D47A5; Thu, 15 Oct 2026 22:35:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792103727; cv=none; b=KAwDiMf7FJwO0tWMyPKs0irH8nGfD1B3GYjXVGrDEivaq0HwSD+Ob7wJk4xSqldWNHMsUOamz9irrJ4tQV8eDWV7xx28z48nupvYF2SbupW3YZej5hqETKwocWu/H86uonVgdSnEaU2MvGjt8QHkZpayPovdMmWpjN8RQEouSKY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792103727; c=relaxed/simple; bh=3E+U6VozkWbJDG0scmCEXfCdyNI3ebUxG20vG9jLttY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=lysCj4z8je6+VmzSnqF3Y+RW/CodSAZhdsdgyoCLK/OFNPck2sVHXQM7MkNqBe9OD2nxeCnseI4TfTKXbzdkED0t5DJN9H6Z/CH3vEyQEUeTXzGzl6nC30hQ7OH1KKLDkKMibhS9LhZTU2P4a7R/hkqJbHdjQuCnwg385iWL/r4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=adw/q6Vo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="adw/q6Vo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51EF71F000C4; Thu, 15 Oct 2026 22:35:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792103724; bh=3NmvYLl5QHeykmporrZNiQW/rnQk5zz4ISSBCPdSjPA=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=adw/q6VoJblAyBzhC05/WcBR3verzhT/2YShYwqZzoW4sOFkXql9e7jy3/0o5mUrI qcQyhCMcrK0yMNYSytMyoqsFrh7KLrgWFmoAU5vPAqTJcVuD7hhWfkiPgZb+e936Y1 1IDP3mgLcv35UuvXZ36snkmcBtFdIgdgKFyFZpskWRHV+7X82j2bh4Q8hDG1ccaX9f UWJJw8V6uVCi4YdA34Xz4qBgSJmwNgnVl7qEt3EOz3lMHW7HL4kBAct18fD5dBYxo1 MIMtFQVosFx4zW+mghjFCQRbjjiTJEUFdfv2YZCvC6CPCVIUqb07W6/yNTGFgmsqwU 0QQsWoVRX5czw== From: Thomas Gleixner To: Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Sebastian Andrzej Siewior , "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 =?utf-8?Q?Wei=C3=9Fschuh?= , Tomas Glozar , Willy Tarreau , x86@kernel.org, Arnd Bergmann Subject: Re: [PATCH v5 2/2] x86: Start removing X86_X32_ABI In-Reply-To: <20261015-x32_removal-v5-2-2bfef9151fad@linutronix.de> References: <20261015-x32_removal-v5-0-2bfef9151fad@linutronix.de> <20261015-x32_removal-v5-2-2bfef9151fad@linutronix.de> Date: Fri, 16 Oct 2026 00:35:22 +0200 Message-ID: <87h5imd239.ffs@fw13> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Oct 15 2026 at 20:47, 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. > > 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 > marking the symbol as BROKEN so it is not possible to enable by default. > If you have a legitimate use case for x32, this is your last chance to > speak up. Otherwise it will be removed. > > Acked-by: Arnd Bergmann > Acked-by: H. Peter Anvin (Rosaic) > Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Thomas Gleixner > --- > arch/x86/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 15fd9ec5ecacb..21a6863e14e7a 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -3104,7 +3104,7 @@ config IA32_EMULATION_DEFAULT_DISABLED > > 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 .note.gnu.property or > # compressed debug sections to x86_x32 properly: > # https://github.com/ClangBuiltLinux/linux/issues/514