Even the same version of TF-A for different platforms would have different feature set.
The other way can be populating a bitmap for various feature during boot time for later use.
This way we don't need someone to keep track of features.

Thanks,
Manish
From: Michal Simek via TF-A <tf-a@lists.trustedfirmware.org>
Sent: 12 January 2023 12:43
To: Varun Wadekar <vwadekar@nvidia.com>; Chris Kay <Chris.Kay@arm.com>; Joanna Farley <Joanna.Farley@arm.com>; Sandrine Bailleux <Sandrine.Bailleux@arm.com>
Cc: tfa-lts@lists.trustedfirmware.org <tfa-lts@lists.trustedfirmware.org>; tf-a@lists.trustedfirmware.org <tf-a@lists.trustedfirmware.org>
Subject: [TF-A] Re: Query BL31 version from NWd
 
Hi,

On 1/12/23 13:24, Varun Wadekar via TF-A wrote:
> Hi,
>
> The Errata ABI only solves part of the problem. We don’t have a discovery
> mechanism for everything that is implemented by the firmware. For example, 
> general bug fixes cannot be discovered. The firmware version is a good
> indicator. It provides some way to track the deployment across multiple
> programs/platforms.
>
> LTS is better positioned as we will introduce more granularity to the firmware
> version thus allowing greater control over deployment. It would be great to ask
> the mainline to use the same versioning scheme. But the mechanism to read the
> firmware version at runtime is missing today.

I don't think that version should be used for any feature checking. We have used
it in past and stop to use it because there is no control over out of tree code.
And it is forcing some dependencies and someone has to keep track of features
present is certain version.
It is good to be aware about version but not for checking any functionality.

It means solid and stable feature discovery mechanism is preferred approach.

Thanks,
Michal
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