From: Frank Rowand <frank.row...@sony.com>
Add ABI documentation for /sys/firmware/fdt
Update contact for /sys/firmware/devicetree/* to include mail list
Signed-off-by: Frank Rowand <frank.row...@sony.com>
---
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 <grant.lik...@linaro.org>
+Contact: Grant Likely <grant.lik...@linaro.org>,
devicet...@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 <frank.row...@sony.com>, devicet...@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 <frank.row...@sony.com>
