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[2620:137:e000::1:20]) by mx.google.com with ESMTP id i187-20020a639dc4000000b005309f24f940si3491479pgd.586.2023.07.10.02.58.30; Mon, 10 Jul 2023 02:58:42 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=d6ONynoz; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233097AbjGJJlZ (ORCPT + 99 others); Mon, 10 Jul 2023 05:41:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232248AbjGJJkE (ORCPT ); Mon, 10 Jul 2023 05:40:04 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14396185; Mon, 10 Jul 2023 02:37:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9C53960F08; Mon, 10 Jul 2023 09:37:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAD20C433C7; Mon, 10 Jul 2023 09:37:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688981878; bh=5Va+D1vw5krsXXAHovHsEdN5okJNaHBciX0Ka1Bh8LI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=d6ONynozQ5yTBS3WIdfoSmySH1DMQUcdlpG87TnWQ/PJ+obKufkZgO3RmSMsbcrAi zBwni1vClKRr6CI8ZxlAA6QtTrrAZqs7elCyzW04nLbF13gDk0t6YtuCjDlyXzoxat DjS0rTX9Y2rHrkkTs8xigbT5sF/U+odpM8JZ8nXKlMEX7Wd7R2BfzAyn5oi09tOlUg OyZeeBpjq95SqZO5pHYdeSKUogtXzvxubYPdyc6yAKLuu6yVSf5ZzoHYADa9G0QxDi HQhrA31+iFzk/tPKy64/KjMRIZ3qUgSwx0NIcgEaWEajdWwlIMXSZTH/HOtZwRlNEg OHdM1WBmoBhZQ== Date: Mon, 10 Jul 2023 10:37:52 +0100 From: Will Deacon To: Maria Yu Cc: corbet@lwn.net, catalin.marinas@arm.com, maz@kernel.org, quic_pkondeti@quicinc.com, quic_kaushalk@quicinc.com, quic_satyap@quicinc.com, quic_shashim@quicinc.com, quic_songxue@quicinc.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm64: Add the arm64.nolse_atomics command line option Message-ID: <20230710093751.GC32673@willie-the-truck> References: <20230710055955.36551-1-quic_aiquny@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230710055955.36551-1-quic_aiquny@quicinc.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 10, 2023 at 01:59:55PM +0800, Maria Yu wrote: > In order to be able to disable lse_atomic even if cpu > support it, most likely because of memory controller > cannot deal with the lse atomic instructions, use a > new idreg override to deal with it. This should not be a problem for cacheable memory though, right? Given that Linux does not issue atomic operations to non-cacheable mappings, I'm struggling to see why there's a problem here. Please can you explain the problem that you are trying to solve? Will