From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6497328F0; Fri, 19 Apr 2024 16:58:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713545916; cv=none; b=OagjQWS019TYUpHKXOISFl7KJekx8gy9Fmtgt2Vfoqi80/L4mHKMSlh2pzpdTMl27DqaFyCbAfhIT7995TE53h5oBwQOd9XB3VIT8FBl4ZTu6D617fqtDE0XLSSjtnnQJtRyUU0r9oj/KpWE3oypJ/4OQan1z1f5BjvJIZMCSgo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713545916; c=relaxed/simple; bh=HIgCb+JE6x/kqPa8JPKJqEjhxyfPx7QjED0kmm5TGiw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tC/TG6c3Qilw9gQwsHYXse1KFtTxpp4MrZ7ssLzUVS6TTDT2za6w96lHoLgFMpVplcspev//J/A8y9p9mLJlz6U/0owXT4nnqYEhW/qWlbtyFj7XSyk9jivQxRswtaSGaNviIwDu23cFn9S0amcZF1A+cEPb9dS+uMbD/8X6Nyc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EDLXBmZ+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EDLXBmZ+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 171ABC072AA; Fri, 19 Apr 2024 16:58:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713545916; bh=HIgCb+JE6x/kqPa8JPKJqEjhxyfPx7QjED0kmm5TGiw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EDLXBmZ+NXfb6opY7MuJxTpeo266f1cEmqQM8duZzC9duFXiqaaX8XRqWBVmOvp7B Pd3pSBAiqX6a7O8yFfFnlfJtUw/gG5x5vbDFHJbin1uEvBc3aIttdSnREvEyrGVffR 614xm7U9Hp2rY8IH7hdr9/FNA9s34y82Gpyj9tmn9jviMXcZaHdIzpcq2TFEHNeflw IWvd9qzowSceuA5o8+wfJcViVCLFRsmLZUSqTYOWcHsu8tFzncBr0TPr6iXsTg9dx0 xPANVXlAuL5k6fq9u1L9+YIGZZKEybdRQLQHed82syMf0swc7yiVCD7EA/gBvyJr9z cvFgOiY2rIddA== Date: Fri, 19 Apr 2024 17:58:26 +0100 From: Will Deacon To: Zayd Qumsieh Cc: Hector Martin , Catalin Marinas , Marc Zyngier , Mark Rutland , Justin Lu , Ryan Houdek , Mark Brown , Ard Biesheuvel , Mateusz Guzik , Anshuman Khandual , Oliver Upton , Miguel Luis , Joey Gouly , Christoph Paasch , Kees Cook , Sami Tolvanen , Baoquan He , Joel Granados , Dawei Li , Andrew Morton , Florent Revest , David Hildenbrand , Stefan Roesch , Andy Chiu , Josh Triplett , Oleg Nesterov , Helge Deller , Zev Weiss , Ondrej Mosnacek , Miguel Ojeda , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Asahi Linux Subject: Re: [PATCH 0/4] arm64: Support the TSO memory model Message-ID: <20240419165826.GB4020@willie-the-truck> References: <20240416022242.89623-1-zayd_qumsieh@apple.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=us-ascii Content-Disposition: inline In-Reply-To: <20240416022242.89623-1-zayd_qumsieh@apple.com> User-Agent: Mutt/1.10.1 (2018-07-13) On Mon, Apr 15, 2024 at 07:22:41PM -0700, Zayd Qumsieh wrote: > >I'm probably going to make myself hugely unpopular here, but I have a > >strong objection to this patch series as it stands. I firmly believe > >that providing a prctl() to query and toggle the memory model to/from > >TSO is going to lead to subtle fragmentation of arm64 Linux userspace. > > It's definitely not our intent to fragment the ecosystem. > The goal of this memory ordering is to simplify emulation layers that benefit from this. > If you have suggestions to reduce the risk of it being misused outside of emulators, we'd be happy to look into it. Once you have exposed this toggle via prctl(), it doesn't really matter what your intentions where. It will get used outside of emulation laters and we'll be stuck supporting it. Will From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B4CAFC4345F for ; Fri, 19 Apr 2024 16:58:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=tHv8ln53h0wAIWrUsbljef9cwofPv0zGXe78O6JFSXU=; b=SQ0QQUakysJXMW Jek1vOxfUA9XVMzievfDPgB2/uNKdwb1tcEiuhzxMRxactz9SjNUEf8GgDureeXth+U0OESrGPSFe LiL39mi116EBpYAJpnhN/dOGMGYZw6GGWUBiF/d9KZcyCd3VzI75OMAI7o7Cwpy6WW/kAMFYZfkqH zs5mK8kQD1vdZS/fGtcfyVA+4euSuIdZHvuR3XwCmQZX7KhprO1tqNperTnFG2Traf/4zUdSbdPNi wZq64oz6V92D7pFw1v6jyrnJtrWRWXifShxPpm3GuAiucOIUZN9CcbgUkxmRKkb5ANkMtNbHMIfuS 09Xi43GRRWWFc5Sudnow==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rxrZQ-00000006T0v-2d1v; Fri, 19 Apr 2024 16:58:40 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rxrZN-00000006Syt-0Dce for linux-arm-kernel@lists.infradead.org; Fri, 19 Apr 2024 16:58:38 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 4EF4561A81; Fri, 19 Apr 2024 16:58:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 171ABC072AA; Fri, 19 Apr 2024 16:58:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713545916; bh=HIgCb+JE6x/kqPa8JPKJqEjhxyfPx7QjED0kmm5TGiw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EDLXBmZ+NXfb6opY7MuJxTpeo266f1cEmqQM8duZzC9duFXiqaaX8XRqWBVmOvp7B Pd3pSBAiqX6a7O8yFfFnlfJtUw/gG5x5vbDFHJbin1uEvBc3aIttdSnREvEyrGVffR 614xm7U9Hp2rY8IH7hdr9/FNA9s34y82Gpyj9tmn9jviMXcZaHdIzpcq2TFEHNeflw IWvd9qzowSceuA5o8+wfJcViVCLFRsmLZUSqTYOWcHsu8tFzncBr0TPr6iXsTg9dx0 xPANVXlAuL5k6fq9u1L9+YIGZZKEybdRQLQHed82syMf0swc7yiVCD7EA/gBvyJr9z cvFgOiY2rIddA== Date: Fri, 19 Apr 2024 17:58:26 +0100 From: Will Deacon To: Zayd Qumsieh Cc: Hector Martin , Catalin Marinas , Marc Zyngier , Mark Rutland , Justin Lu , Ryan Houdek , Mark Brown , Ard Biesheuvel , Mateusz Guzik , Anshuman Khandual , Oliver Upton , Miguel Luis , Joey Gouly , Christoph Paasch , Kees Cook , Sami Tolvanen , Baoquan He , Joel Granados , Dawei Li , Andrew Morton , Florent Revest , David Hildenbrand , Stefan Roesch , Andy Chiu , Josh Triplett , Oleg Nesterov , Helge Deller , Zev Weiss , Ondrej Mosnacek , Miguel Ojeda , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Asahi Linux Subject: Re: [PATCH 0/4] arm64: Support the TSO memory model Message-ID: <20240419165826.GB4020@willie-the-truck> References: <20240416022242.89623-1-zayd_qumsieh@apple.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240416022242.89623-1-zayd_qumsieh@apple.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240419_095837_162548_13A54A14 X-CRM114-Status: GOOD ( 14.38 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Apr 15, 2024 at 07:22:41PM -0700, Zayd Qumsieh wrote: > >I'm probably going to make myself hugely unpopular here, but I have a > >strong objection to this patch series as it stands. I firmly believe > >that providing a prctl() to query and toggle the memory model to/from > >TSO is going to lead to subtle fragmentation of arm64 Linux userspace. > > It's definitely not our intent to fragment the ecosystem. > The goal of this memory ordering is to simplify emulation layers that benefit from this. > If you have suggestions to reduce the risk of it being misused outside of emulators, we'd be happy to look into it. Once you have exposed this toggle via prctl(), it doesn't really matter what your intentions where. It will get used outside of emulation laters and we'll be stuck supporting it. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel