From mboxrd@z Thu Jan 1 00:00:00 1970 From: zhaoshenglong@huawei.com (Shannon Zhao) Date: Mon, 7 Dec 2015 16:58:30 +0800 Subject: [Xen-devel] [PATCH v3 07/62] arm/acpi: Add arch_acpi_os_map_memory helper function for ARM In-Reply-To: <565C6198.3070805@citrix.com> References: <1447753261-7552-1-git-send-email-shannon.zhao@linaro.org> <1447753261-7552-8-git-send-email-shannon.zhao@linaro.org> <565C6198.3070805@citrix.com> Message-ID: <56654A36.6070708@huawei.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On 2015/11/30 22:47, Julien Grall wrote: > Hi, > > On 23/11/15 11:37, Stefano Stabellini wrote: >> > On Tue, 17 Nov 2015, shannon.zhao at linaro.org wrote: >>> >> From: Shannon Zhao >> > could you please add a couple of lines to the commit message mentioning >> > why __va(phys) is an acceptable implementation of arch_acpi_os_map_memory? > FWIW, I already asked this question multiple time on the previous series > without clear answer. > > __va should only be used when the memory is direct-mapped to Xen (i.e > accessible directly). On ARM64, this is only the case for the RAM. Can > someone confirm the ACPI will always reside to the RAM? I checked this with the UEFI SPEC. It says in 2.3.6 AArch64 Platforms: "If ACPI is supported : ? ACPI Tables loaded at boot time can be contained in memory of type EfiACPIReclaimMemory (recommended) or EfiACPIMemoryNVS." So I think it means the ACPI tables will always reside in RAM. Thanks, -- Shannon