Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752175Ab3FYSGX (ORCPT ); Tue, 25 Jun 2013 14:06:23 -0400 Received: from mail-wi0-f182.google.com ([209.85.212.182]:45510 "EHLO mail-wi0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752047Ab3FYSGU (ORCPT ); Tue, 25 Jun 2013 14:06:20 -0400 From: Leif Lindholm To: linux-arm-kernel@lists.infradead.org Cc: linux-efi@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, patches@linaro.org, hpa@linux.intel.com, tglx@linutronix.de, matt.fleming@intel.com, Leif Lindholm Subject: [PATCH 1/4] Documentation: arm: [U]EFI runtime services Date: Tue, 25 Jun 2013 19:11:00 +0100 Message-Id: <1372183863-11333-2-git-send-email-leif.lindholm@linaro.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1372183863-11333-1-git-send-email-leif.lindholm@linaro.org> References: <1372183863-11333-1-git-send-email-leif.lindholm@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2823 Lines: 74 This patch provides documentation of the [U]EFI runtime services and configuration features. Signed-off-by: Leif Lindholm --- Documentation/arm/00-INDEX | 3 +++ Documentation/arm/uefi.txt | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+) create mode 100644 Documentation/arm/uefi.txt diff --git a/Documentation/arm/00-INDEX b/Documentation/arm/00-INDEX index 4978456..87e01d1 100644 --- a/Documentation/arm/00-INDEX +++ b/Documentation/arm/00-INDEX @@ -36,3 +36,6 @@ nwfpe/ - NWFPE floating point emulator documentation swp_emulation - SWP/SWPB emulation handler/logging description + +uefi.txt + - [U]EFI configuration and runtime services documentation diff --git a/Documentation/arm/uefi.txt b/Documentation/arm/uefi.txt new file mode 100644 index 0000000..5c48271 --- /dev/null +++ b/Documentation/arm/uefi.txt @@ -0,0 +1,39 @@ +The nomenclature EFI and UEFI are used interchangeably in this document. + +The implementation depends on receiving pointers to the UEFI memory map +and System Table in a Flattened Device Tree - so is only available with +CONFIG_OF. + +It (early) parses the FDT for the following parameters: +- 'efi-system-table': + Physical address of the system table. (required) +- 'efi-runtime-mmap': + Physical address of an EFI memory map, containing at least + the regions to be preserved. (required) +- 'efi-runtime-mmap-size': + Size in bytes of the provided memory map. (required) +- 'efi-mmap-desc-size': + Size of each descriptor in the memory map. (override default) +- 'efi-mmap-desc-ver': + Memory descriptor format version. (override default) + +Since UEFI firmware on ARM systems are required to use a 1:1 memory map +even on LPAE-capable systems, the above fields are 32-bit regardless. + +It also depends on early_ioremap to parse the memory map and preserve +the regions required for runtime services. + +For actually enabling [U]EFI support, enable: +- CONFIG_EFI=y +- CONFIG_EFI_VARS=y or m + +After the kernel has mapped the required regions into its address space, +a SetVirtualAddressMap() call is made into UEFI in order to update +relocations. This call must be performed with all the code in a 1:1 +mapping. This implementation achieves this by temporarily disabling the +MMU for the duration of this call. This can only be done safely: +- before secondary CPUs are brought online. +- after early_initcalls have completed, sinze it uses setup_mm_for_reboot(). + +For verbose debug messages, specify 'uefi_debug' on the kernel command +line. -- 1.7.10.4 -- 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/