Re: [PATCH v18 2/7] firmware: arm_rmm: Check for RMI support at init

[Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>]

On Mon, 21 Sep 2026 10:00:20 +0100
Suzuki K Poulose <suzuki.poulose@arm.com> wrote:

> On 19/09/2026 02:27, Jonathan Cameron wrote:
> >> Query the RMI version number and check if it is a compatible version.
> >> The first two feature registers are read and exposed for future code to
> >> use.
> >>
> >> We only support this for Little Endian kernels, the Big Endian kernel
> >> support is anyway marked BROKEN and is being removed.  
> > 
> > Can we have a small comment here on why the default is y
> > 
> > It's a big thing to opt into by default.  Feels like defconfig
> > material maybe but not in the Kconfig defaults unless I'm missing
> > something.  
> 
> We need this for KVM arm64. I could drop the default here and
> KVM selects this anyways. But, how far do we go on this ?
> Do we need to be able to disable this completely even for KVM ?

Not sure. Question for the KVM folk to decide.  Lot of pre CCA systems
out there and domains in which CCA may not be useful,
so definitely makes sense that people will build kernels
without it.  

I think dropping this default though makes sense if KVM
can select it. 

Jonathan

> 
> As such it is a relatively smaller blob:
> 
> $ size drivers/firmware/arm_rmm/rmi.o
>     text    data     bss     dec     hex filename
>     7477     572       1    8050    1f72 drivers/firmware/arm_rmm/rmi.o
> 
> Cheers
> Suzuki
>