From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4A5C6146017; Fri, 21 Jun 2024 20:32:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.175.24.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719001949; cv=none; b=tkR4Sy919mlfV9dDsw8BBMtQtGAHVMKpBxDuPjvvndHcaWF256KgawbF1uIs+VLWIRr3RZGNAaVLN805Vp7pjPs/YPeO7q7ipPtnfKqk4GgIyTAg6cuVPDDvLhySXyfnw4yEbNnMRNyMvdyWvmYkdI8I9qbieLn4KPKHNjy6mJo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719001949; c=relaxed/simple; bh=gE2ViUah1IOM2sFBbFJHidv3pjaO7zrqCmYujLwwOeg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ESmNV8oIOLVwt9jqDr3xRwOFBeoxiKPe2wbZ/Mn3F+ZRB5/B7i9fCMl7rrPIsZIxWyRYAsMCJ0WSVLpyVLcRm5TqberqoRyuVMtMx/sVVwoeCvLMCVMuN6NxuDvFNiu6oE1IbTb4g06R2v6Vzxjl5nuQ4UpmB1G34sBia78eLWc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de; spf=pass smtp.mailfrom=alpha.franken.de; arc=none smtp.client-ip=193.175.24.41 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alpha.franken.de Received: from uucp by elvis.franken.de with local-rmail (Exim 3.36 #1) id 1sKkva-0000N7-00; Fri, 21 Jun 2024 22:32:10 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 6A9EFC0120; Fri, 21 Jun 2024 22:31:21 +0200 (CEST) Date: Fri, 21 Jun 2024 22:31:21 +0200 From: Thomas Bogendoerfer To: Jiaxun Yang Cc: "Maciej W. Rozycki" , Jonas Gorski , "linux-mips@vger.kernel.org" , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/4] MIPS: Introduce config options for LLSC availability Message-ID: References: <20240612-mips-llsc-v2-0-a42bd5562bdb@flygoat.com> <20240612-mips-llsc-v2-2-a42bd5562bdb@flygoat.com> <2c26a07f-fa68-48f1-8f3b-3b5e4f77130b@app.fastmail.com> <83cf475c-86a3-4acb-bc82-d94c66c53779@app.fastmail.com> Precedence: bulk X-Mailing-List: linux-mips@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: <83cf475c-86a3-4acb-bc82-d94c66c53779@app.fastmail.com> On Fri, Jun 21, 2024 at 04:21:49PM +0100, Jiaxun Yang wrote: > Does anyone reckon the reason behind opt-out LLSC for IP28? As far as I understand > there is no restriction on using LLSC after workaround being applied. If it's purely > performance reason, I think I'll need to move kernel_uses_llsc logic to Kconfig as well. commit 46dd40aa376c8158b6aa17510079caf5c3af6237 Author: Thomas Bogendoerfer Date: Wed Oct 7 12:17:04 2020 +0200 MIPS: SGI-IP28: disable use of ll/sc in kernel SGI-IP28 systems only use broken R10k rev 2.5 CPUs, which could lock up, if ll/sc sequences are issued in certain order. Since those systems are all non-SMP, we can disable ll/sc usage in kernel. Signed-off-by: Thomas Bogendoerfer Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]