Re: [PATCH v3 1/8] dt-bindings: arm: Add Live Firmware Activation

[Andre Przywara <andre.przywara@arm.com>]

Hi,

sorry, just figured that I never replied to this - was stuck in my Draft 
folder ...

On 7/17/26 10:38, Sudeep Holla wrote:
> On Mon, Jul 06, 2026 at 03:44:41PM +0200, Andre Przywara wrote:
>> The Arm Live Firmware Activation spec [1] describes updating firmware
>> images during runtime, without requiring a reboot. Update images might
>> be deployed out-of-band, for instance via a BMC, in this case the OS
>> needs to be notified about the availability of a new image.
>>
>> Describe an interrupt that could be triggered by the platform, to notify
>> about any changes.
>>
>> [1] https://developer.arm.com/documentation/den0147/latest/
>>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>>   .../devicetree/bindings/arm/arm,lfa.yaml      | 45 +++++++++++++++++++
>>   1 file changed, 45 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/arm/arm,lfa.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/arm/arm,lfa.yaml b/Documentation/devicetree/bindings/arm/arm,lfa.yaml
>> new file mode 100644
>> index 000000000000..ef8e250f2da7
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/arm,lfa.yaml
>> @@ -0,0 +1,45 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/arm/arm,lfa.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Arm Live Firmware Activation (LFA)
>> +
>> +maintainers:
>> +  - Andre Przywara <andre.przywara@arm.com>
>> +  - Sudeep Holla <sudeep.holla@arm.com>
>> +
>> +description:
>> +  The Arm Live Firmware Activation (LFA) specification [1] describes a
>> +  firmware interface to activate an updated firmware at runtime, without
>> +  requiring a reboot. Updates might be supplied out-of-band, for instance
>> +  via a BMC, in which case the platform needs to notify an OS about pending
>> +  image updates.
> 
> What does the below described "interrupts" cover or doesn't cover? Both
> in case of in-band and out-of-band. It is not very clear for me.

DEN0147 says (at the very end of the document):
"As of this version of the specification, the expected scope would be 
notification to the Operating System to indicate new LFA updates are 
available."
In-band updates are work in progress, spec-wise, and we would cover this 
when it has arrived. So for now this if for out-of-band updates, so that 
a BMC for instance can signal the arrival of an updated image to the OS.
I clarified the wording in the description of the interrupt property. I 
also added that it must be an edge triggered IRQ, as there is no easy 
way to signal completion, and the ACPI notification has the same semantics.

Cheers,
Andre.