Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757555AbbBENz2 (ORCPT ); Thu, 5 Feb 2015 08:55:28 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57900 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753137AbbBENz0 (ORCPT ); Thu, 5 Feb 2015 08:55:26 -0500 Message-ID: <1423144447.18187.110.camel@deneb.redhat.com> Subject: Re: [PATCH v8 02/21] acpi: fix acpi_os_ioremap for arm64 From: Mark Salter To: Catalin Marinas 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" Date: Thu, 05 Feb 2015 08:54:07 -0500 In-Reply-To: <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> <20150205104149.GA18158@e104818-lin.cambridge.arm.com> Organization: Red Hat, Inc Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1744 Lines: 39 On Thu, 2015-02-05 at 10:41 +0000, Catalin Marinas wrote: > 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. The problem with kmap() is that it only maps a single page. I've seen tables over 4k which is why I patched acpi_map() not to use kmap() 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)? > -- 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/