Re: [PATCH v11 7/7] coco: guest: arm64: Replace dummy CCA device with sysfs ABI

[Catalin Marinas]

On Mon, Sep 14, 2026 at 11:35:11AM +0530, Aneesh Kumar K.V (Arm) wrote:
> The SMCCC firmware driver now creates the arm-smccc platform device and

Nit: we now have devices on an arm_smccc bus, so this first line doesn't
make sense.

> instantiates the CCA RSI auxiliary devices once the RSI ABI is discovered.
> The arm64-specific arm-cca-dev platform device stub is therefore no longer
> needed.
> 
> However, userspace has used the arm-cca-dev platform device to detect Arm
> CCA Realm guests [1]. Removing it without a replacement would break that
> detection and would also leave userspace depending on kernel device-model
> details.

Well, removing it would break the ABI even if you replace it with
something else. But I think we agreed it wasn't great for systemd to
depend on the old interface either. Assuming systemd can be fixed (and
the fix backported) and no production deployments are affected, I'm fine
with this.

Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>