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of: document /sys/firmware/fdt

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Add ABI documentation for /sys/firmware/fdt

Update contact email for /sys/firmware/devicetree/* and add mail list

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Acked-by: Grant Likely <grant.likely@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
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Frank Rowand 2017-06-28 15:21:46 -07:00 committed by Rob Herring
parent ce437750e8
commit 5e1743c0af
1 changed files with 25 additions and 1 deletions
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Documentation/ABI/testing/sysfs-firmware-ofw
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@ -1,6 +1,6 @@
What: /sys/firmware/devicetree/*
Date: November 2013
Contact: Grant Likely <grant.likely@linaro.org>
Contact: Grant Likely <grant.likely@arm.com>, 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 +26,27 @@ 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 <frowand.list@gmail.com>, 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