From: Frank Rowand <[email protected]> Add ABI documentation for /sys/firmware/fdt
Change obsolete contact for /sys/firmware/devicetree/* to mail list Signed-off-by: Frank Rowand <[email protected]> --- 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 <[email protected]> +Contact: [email protected] 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: [email protected] +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 <[email protected]>
