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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46FF8C433DB for ; Wed, 6 Jan 2021 12:36:48 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EB74A22B45 for ; Wed, 6 Jan 2021 12:36:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EB74A22B45 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject: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=ewb/C42SjnbrvRyhIDH5Yqmzu3Y2zLxSSN3FMSQwYco=; b=S9Ar6rWHTu4WCMDbKyPSUH1Py CcPdFYpF9DogZCMsLeedtQujeTmDwSDaUjxosYaUADjfSbTZ/8ycLdihRLes9b2kXXjT+ZqPT87P/ s/qKNMAq0S7ZsSkOc/Iin0MIspY6AeJ9sqm9PXczZK+zhIEceOfeKe/r09EWnE0G243epYrLEcRhM z7iO4mXKAPZ8kI1X8QsKMBXcYf1/iE5HMc3EEQAF32tOt0XZzczTjazRLstIftB0USeZpEmeR9a01 P5xhJMDzDli/s2M0ze5NZ4jGgI9UFxXLnLu3qWboravW50VgMRvNbt4PARE/4uDAcXRki/mvnVf2i NDGFTUGmw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kx81Q-0000et-Li; Wed, 06 Jan 2021 12:34:40 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kx81N-0000eS-QY for linux-arm-kernel@lists.infradead.org; Wed, 06 Jan 2021 12:34:38 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7E89C22B45; Wed, 6 Jan 2021 12:34:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1609936476; bh=WgvS4tF0ZWeikogI4MPn+X49EO/EQE73OKs1GUuXPQE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lPOUFq+XVi71GLdZCBjNfOCg1jfxK8gz0CU5GEub44Xa0fymuPVqY+UyLAUMNkVV5 tqurSMZBFf+ZQQOeYLM3tG3OlRH+AWQkDEuwuPtl2YfFwO6kKQxs8KCziudccpJE/2 l7EFTWJozxaQ7TEKT6ApaQyqYV8QZqwCIUYwneBiZgEbQ+Q44YtEfDf2qfSKI6bgSv K3vTBX86Ty9irVqM8ZRMW3RLKRmrhcBGmkRpIUbAqsgiZg4gjXh7n/CBk/mhvvQyOn RRDdZppLVeAqtS5DxGTGWcUDjBI+cifQNPDdlYjApjy28uyWFHEl2x/3X5aa3vRXU6 AJVD3+2E0ewsQ== Date: Wed, 6 Jan 2021 12:34:28 +0000 From: Will Deacon To: "Isaac J. Manjarres" Subject: Re: [PATCH RESEND 0/7] iommu: Permit modular builds of io-pgtable drivers Message-ID: <20210106123428.GA1798@willie-the-truck> References: <1609832205-10055-1-git-send-email-isaacm@codeaurora.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1609832205-10055-1-git-send-email-isaacm@codeaurora.org> 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-20210106_073437_948968_6C6AA8F3 X-CRM114-Status: GOOD ( 13.93 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel-team@android.com, tomeu.vizoso@collabora.com, pdaly@codeaurora.org, airlied@linux.ie, robin.murphy@arm.com, joro@8bytes.org, iommu@lists.linux-foundation.org, dri-devel@lists.freedesktop.org, steven.price@arm.com, robdclark@gmail.com, alyssa.rosenzweig@collabora.com, daniel@ffwll.ch, freedreno@lists.freedesktop.org, sean@poorly.run, linux-arm-kernel@lists.infradead.org, pratikp@codeaurora.org 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, Jan 04, 2021 at 11:36:38PM -0800, Isaac J. Manjarres wrote: > The goal of the Generic Kernel Image (GKI) effort is to have a common > kernel image that works across multiple Android devices. This involves > generating a kernel image that has core features integrated into it, > while SoC specific functionality can be added to the kernel for the > device as a module. > > Along with modularizing IOMMU drivers, this also means building the > io-pgtable code as modules, which allows for SoC vendors to only include > the io-pgtable implementations that they use. For example, GKI for arm64 > must include support for both the IOMMU ARM LPAE/V7S formats at the > moment. Having the code for both formats as modules allows SoC vendors > to only provide the page table format that they use, along with their > IOMMU driver. Why is this desirable for upstream? This code isn't especially large, and the formats we support are largely architectural, meaning that they are shared between different IOMMU drivers. I think that making this modular just means that out-of-tree modifications are likely to generate page-tables which are specific to a particular IOMMU, and lead to horrible problems (crashes and data corruption) if another IOMMU driver tries to use them. Please can you upstream whatever changes you want to make instead? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel