Re: [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays

From: Rob Herring
Date: Tue Oct 20 2015 - 16:57:21 EST


On Tue, Oct 20, 2015 at 2:13 PM, Pantelis Antoniou
<pantelis.antoniou@xxxxxxxxxxxx> wrote:
> Documentation ABI entry for overlays sysfs entries.
>
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
> ---
> .../ABI/testing/sysfs-firmware-devicetree-overlays | 40 ++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
>
> diff --git a/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
> new file mode 100644
> index 0000000..adc4068
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
> @@ -0,0 +1,40 @@
> +What: /sys/firmware/devicetree/overlays/
> +Date: October 2015
> +Contact: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
> +Description:
> + This directory contains the applied device tree overlays of
> + the running system, as directories of the overlay id.
> +
> + enable: The master enable switch, by default is 1, and when
> + set to 0 it cannot be re-enabled for security reasons.
> +
> + The discussion about this switch takes place in:
> + http://comments.gmane.org/gmane.linux.drivers.devicetree/101871
> +
> + Kees Cook:
> + "Coming from the perspective of drawing a bright line between
> + kernel and the root user (which tends to start with disabling
> + kernel module loading), I would say that there at least needs
> + to be a high-level one-way "off" switch for the interface so
> + that systems that have this interface can choose to turn it off
> + during initial boot, etc."
> +
> +What: /sys/firmware/devicetree/overlays/<id>
> +Date: October 2015
> +Contact: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
> +Description:
> + Each directory represents an applied overlay, containing
> + the following attribute files.
> +
> + can_remove: The attribute set to 1 means that the overlay can
> + be removed, while 0 means that the overlay is being
> + overlapped therefore removal is prohibited.
> +
> +What: /sys/firmware/devicetree/overlays/<id>/<fragment-name>/
> +Date: October 2015
> +Contact: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
> +Description:
> + Each of these directories contain information about of the
> + particular overlay fragment.
> +
> + target: The full-path of the target of the fragment
> --

What happened to attributes within the fragment dir?

Rob
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