Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752899AbbBEKmP (ORCPT ); Thu, 5 Feb 2015 05:42:15 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:41895 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751060AbbBEKmN (ORCPT ); Thu, 5 Feb 2015 05:42:13 -0500 Date: Thu, 5 Feb 2015 10:41:49 +0000 From: Catalin Marinas To: Mark Salter Cc: "Rafael J. Wysocki" , "hanjun.guo@linaro.org" , Olof Johansson , Arnd Bergmann , Mark Rutland , "grant.likely@linaro.org" , Will Deacon , Lorenzo Pieralisi , "graeme.gregory@linaro.org" , Sudeep Holla , "jcm@redhat.com" , Jason Cooper , Marc Zyngier , Bjorn Helgaas , Daniel Lezcano , Mark Brown , Rob Herring , Robert Richter , Randy Dunlap , Charles Garcia-Tobin , "phoenix.liyi@huawei.com" , Timur Tabi , Ashwin Chaugule , "suravee.suthikulpanit@amd.com" , Mark Langsdorf , "wangyijing@huawei.com" , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linaro-acpi@lists.linaro.org" Subject: Re: [PATCH v8 02/21] acpi: fix acpi_os_ioremap for arm64 Message-ID: <20150205104149.GA18158@e104818-lin.cambridge.arm.com> References: <1422881149-8177-1-git-send-email-hanjun.guo@linaro.org> <1422881149-8177-3-git-send-email-hanjun.guo@linaro.org> <2422968.Es7R0p3loO@vostro.rjw.lan> <1422984576.18187.82.camel@deneb.redhat.com> <20150204112508.GB26006@e104818-lin.cambridge.arm.com> <1423066107.18187.99.camel@deneb.redhat.com> <20150204175734.GI26006@e104818-lin.cambridge.arm.com> <1423076294.18187.103.camel@deneb.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1423076294.18187.103.camel@deneb.redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1495 Lines: 33 On Wed, Feb 04, 2015 at 06:58:14PM +0000, Mark Salter wrote: > On Wed, 2015-02-04 at 17:57 +0000, Catalin Marinas wrote: > > On Wed, Feb 04, 2015 at 04:08:27PM +0000, Mark Salter wrote: > > > acpi_os_remap() is used to map ACPI tables. These tables may be in ram > > > which are already included in the kernel's linear RAM mapping. So we > > > need ioremap_cache to avoid two mappings to the same physical page > > > having different caching attributes. > > > > What's the call path to acpi_os_ioremap() on such tables already in the > > linear mapping? I can see an acpi_map() function which already takes > > care of the RAM mapping case but there are other cases where > > acpi_os_ioremap() is called directly. For example, > > acpi_os_read_memory(), can it be called on both RAM and I/O? > > acpi_map() is the one I've seen. By default, if should_use_kmap() is not patched for arm64, it translates to page_is_ram(); acpi_map() would simply use a kmap() which returns the current kernel linear mapping on arm64. > I'm not sure about others. Question for the ARM ACPI guys: what happens if you implement acpi_os_ioremap() on arm64 as just ioremap()? Do you get any WARN_ON() (__ioremap_caller() checks whether the memory is RAM)? -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/