From mboxrd@z Thu Jan 1 00:00:00 1970 From: timur@codeaurora.org (Timur Tabi) Date: Thu, 29 Jan 2015 12:34:50 -0600 Subject: [Linaro-acpi] [PATCH v7 04/17] ARM64 / ACPI: Introduce early_param for "acpi" and pass acpi=force to enable ACPI In-Reply-To: References: <1421247905-3749-1-git-send-email-hanjun.guo@linaro.org> <1421247905-3749-5-git-send-email-hanjun.guo@linaro.org> <20150128181453.GG31752@e104818-lin.cambridge.arm.com> <54C92804.5090806@codeaurora.org> <20150129151956.GF8951@e104818-lin.cambridge.arm.com> <54CA7A42.5080800@codeaurora.org> Message-ID: <54CA7D4A.5090709@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/29/2015 12:28 PM, Ard Biesheuvel wrote: > The UEFI stub in the kernel uses the DTB file format (FDT) to pass > information about the UEFI memory map and system table to the kernel. > It does so even if there is no device tree that describes the > platform. In this case, the file only contains a /chosen DT node, and > nothing else, and it is up to the kernel to figure out that it can ask > UEFI for a set of ACPI tables that it can use instead to configure the > system. Otherwise, the /chosen node properties are added to a device > tree that contains the full platform description. > > The problem is that we have to decide how to distinguish a > conventional device tree DTB from a DTB that only exists to > communicate the UEFI entry points. Ah, that's exactly what I'm seeing. The UEFI stub in our kernel generates a DTB, and therefore I always need to put acpi=force on our kernel command line. -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.