[PATCH v2] of: document /sys/firmware/fdt

[PATCH v2] of: document /sys/firmware/fdt

[frowand.list]

From: Frank Rowand <frank.rowand@sony.com>

Add ABI documentation for /sys/firmware/fdt

Change obsolete contact for /sys/firmware/devicetree/* to mail list

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
---

changes from v1:
  - Remove obsolete email address as contact for /sys/firmware/devicetree/*
  - For newly documented /sys/firmware/fdt do not include any individual
    email for Contact (only provide email list)

 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..30a6b3621828 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.likely@linaro.org>
+Contact:	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:	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 <frank.rowand@sony.com>

Re: [PATCH v2] of: document /sys/firmware/fdt

[Frank Rowand]

Hi Rob,

Please ignore this version, Grant replied to your v1 comment, so
I'll spin a v3.

-Frank

On 06/28/17 14:53, frowand.list@gmail.com wrote:
> From: Frank Rowand <frank.rowand@sony.com>
> 
> Add ABI documentation for /sys/firmware/fdt
> 
> Change obsolete contact for /sys/firmware/devicetree/* to mail list
> 
> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
> ---
> 
> changes from v1:
>   - Remove obsolete email address as contact for /sys/firmware/devicetree/*
>   - For newly documented /sys/firmware/fdt do not include any individual
>     email for Contact (only provide email list)
> 
>  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..30a6b3621828 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.likely@linaro.org>
> +Contact:	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:	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
> +
>