Re: [RFC PATCH v1] imagebuilder: Add a script to check the sanity of device tree

[Ayan Kumar Halder <ayankuma@amd.com>]

Hi,

On 01/09/2025 14:51, Ayan Kumar Halder wrote:
> Hi Michal,
>
> On 01/09/2025 14:17, Orzel, Michal wrote:
>>
>> On 01/09/2025 14:31, Ayan Kumar Halder wrote:
>>> Xen gives a panic if certain nodes are not present in the device 
>>> tree. In order
>>> to prevent this panic, scripts/dt_sanity.py is written so that it 
>>> checks if the
>>> node/s are present. If the node/s are not present, the script gives 
>>> an error.
>>>
>>> User is expected to run the script against the device tree before 
>>> booting Xen
>>> with dtb.
>>
One thing I forgot to mention is that as part of safety certification, 
we do need to do "Failure mode and error analysis". This means 
describing the scenarios in which Xen can fail to perform its regular 
functionality and coming up with prevention, detection and mitigation 
measures.

One can argue that the panics caused by system misconfiguration, are the 
most straightforward of all the errors. However, we do need to define 
prevention mechanisms to avoid these panics. For this particular 
failure, the prevention mechanism can be described as manually looking 
into the device tree to ensure that the nodes expected by Xen, are 
present. The script aims to provide a better alternative.

This script is not meant to catch all possible panics. However we do 
want to have such scripts and utilities wherever possible, and document 
them as part of our FMEA.

May be a safety expert can comment if the approach makes sense.

- Ayan