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 0175FC7115B for ; Thu, 19 Jun 2025 17:02:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type: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=tlwQdO4suNstERVRsNsnemjpPAsRvO4R1t9ZtoyagAo=; b=R5axbYaHoUf6TXYHBkjDLJHSj/ ok+wDwZ6/SbLN/yABpRj6bVt8Jrifz7T0WnUAtVd5l0MYpoXEfPaKPCDGbHGPUBg+lmqspu6QLD0f 1WBENBNkjJjiBHMnQmU852qGy5hOBcgzxnBz8F3kNSTRXupglyA+HSESLzX0A2LZvkSNrxozQcK61 qqh7bMXIYJr8perD5N/uyeBqnaQbb8NkSzCMvDaB37MsMbehdGzii7UXEnfMahWKiNHD/k8Ac7D6U bvFVxec+bDBqWxC1YlkQdzg26ouzubEHGurd9qIXW1UZSgJ0OAdiVkjRd7S6ZB5R4jrUluf62sdkX MLGwoyMA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uSIeg-0000000DepQ-3jhA; Thu, 19 Jun 2025 17:02:26 +0000 Received: from nyc.source.kernel.org ([147.75.193.91]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uSFaj-0000000DDTC-06rv for linux-arm-kernel@lists.infradead.org; Thu, 19 Jun 2025 13:46:10 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 11529A545C0; Thu, 19 Jun 2025 13:46:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B68DFC4CEEF; Thu, 19 Jun 2025 13:46:03 +0000 (UTC) Date: Thu, 19 Jun 2025 14:46:01 +0100 From: Catalin Marinas To: =?utf-8?Q?Miko=C5=82aj?= Lenczewski Cc: ryan.roberts@arm.com, yang@os.amperecomputing.com, will@kernel.org, jean-philippe@linaro.org, robin.murphy@arm.com, joro@8bytes.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, james.morse@arm.com, broonie@kernel.org, ardb@kernel.org, baohua@kernel.org, suzuki.poulose@arm.com, david@redhat.com, jgg@ziepe.ca, nicolinc@nvidia.com, jsnitsel@redhat.com, mshavit@google.com, kevin.tian@intel.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev Subject: Re: [PATCH v7 2/4] arm64: Add BBM Level 2 cpu feature Message-ID: References: <20250617095104.6772-1-miko.lenczewski@arm.com> <20250617095104.6772-3-miko.lenczewski@arm.com> <20250619115132.GA20673@e133081.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250619115132.GA20673@e133081.arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250619_064609_128788_0807B652 X-CRM114-Status: GOOD ( 15.42 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jun 19, 2025 at 12:51:32PM +0100, Mikołaj Lenczewski wrote: > On Thu, Jun 19, 2025 at 12:05:05PM +0100, Catalin Marinas wrote: > > On Tue, Jun 17, 2025 at 09:51:02AM +0000, Mikołaj Lenczewski wrote: > > > + * whether the MIDR check passes. This is because we specifically > > > + * care only about a stricter form of BBML2 (one guaranteeing noabort), > > > + * and so the MMFR2 check is pointless (all implementations passing the > > > + * MIDR check should also pass the MMFR2 check). > > > > I think there's at least one implementation that behaves as > > BBML2-noabort but does not have the ID field advertising BBML2. > > > > Yes, I put "should" instead of "will" because of the AmpereOne > situation, but I didn't want to "name and shame". Should I explicitly > call this out? Or would you like me to soften the vocabulary here to imply > that as long as the MIDR passes, the MMFR2 check is not important? I missed the "should" part. Anyway, I would just drop the explanation from "This is because...". -- Catalin