Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750768AbdFNEVE (ORCPT ); Wed, 14 Jun 2017 00:21:04 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:36429 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750721AbdFNEVC (ORCPT ); Wed, 14 Jun 2017 00:21:02 -0400 From: frowand.list@gmail.com To: Rob Herring Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] of: document /sys/firmware/fdt Date: Tue, 13 Jun 2017 21:20:07 -0700 Message-Id: <1497414007-8380-1-git-send-email-frowand.list@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2149 Lines: 54 From: Frank Rowand Add ABI documentation for /sys/firmware/fdt Update contact for /sys/firmware/devicetree/* to include mail list Signed-off-by: Frank Rowand --- Documentation/ABI/testing/sysfs-firmware-ofw | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-firmware-ofw b/Documentation/ABI/testing/sysfs-firmware-ofw index f562b188e71d..8e700db6c295 100644 --- a/Documentation/ABI/testing/sysfs-firmware-ofw +++ b/Documentation/ABI/testing/sysfs-firmware-ofw @@ -1,6 +1,6 @@ What: /sys/firmware/devicetree/* Date: November 2013 -Contact: Grant Likely +Contact: Grant Likely , devicetree@vger.kernel.org Description: When using OpenFirmware or a Flattened Device Tree to enumerate hardware, the device tree structure will be exposed in this @@ -26,3 +26,28 @@ Description: name plus address). Properties are represented as files in the directory. The contents of each file is the exact binary data from the device tree. + +What: /sys/firmware/fdt +Date: February 2015 +KernelVersion: 3.19 +Contact: Frank Rowand , devicetree@vger.kernel.org +Description: + Exports the FDT blob that was passed to the kernel by + the bootloader. This allows userland applications such + as kexec to access the raw binary. This blob is also + useful when debugging since it contains any changes + made to the blob by the bootloader. + + The fact that this node does not reside under + /sys/firmware/device-tree is deliberate: FDT is also used + on arm64 UEFI/ACPI systems to communicate just the UEFI + and ACPI entry points, but the FDT is never unflattened + and used to configure the system. + + A CRC32 checksum is calculated over the entire FDT + blob, and verified at late_initcall time. The sysfs + entry is instantiated only if the checksum is valid, + i.e., if the FDT blob has not been modified in the mean + time. Otherwise, a warning is printed. +Users: kexec, debugging + -- Frank Rowand