Hi,
On 10/14/26 10:12, Rahul Pathak wrote:
Hi Michal,
It is not correct to say that SCMI already exists and so RPMI is not
needed. If you read the RPMI specification you will find that the two
differ significantly. I don't mean overlapping names, but how things
are defined and implemented in the spec. Compare the transport,
compare the defined messages.
RPMI defines many service groups that have no counterpart in SCMI like
System MSI/System IRQ, TEE, RAS Agent, Management Mode, CPPC,
Logging, Request Forward and others. Together they cover use cases
ranging from typical systems to confidential computing and
virtualization, all in one specification.
There is also a difference in governance, which is visible from the
licences of the two specifications.
RPMI is under CC-BY 4 license which allows anyone to adapt it and share
modified versions with attribution, and changes are developed in
the open under RISC-V International. The development does not happen
behind closed door but rather any indivudial/organization can also take part in
the discussions.
I don't think license is an argument here because someone decided not to talk to
ARM about it. Based on my information none really talked to ARM to change that
license for SCMI (if that was an issue) or move it to neutral place.
I have already talked to ARM about it.
I think open source projects always give users/vendors freedom
to use any protocol which suits their platform. It must not be dictated
that everyone must stick to one interface. As Heinrich pointed out that U-Boot
already supports alternatives for various things and
Linux and OpenSBI already support RPMI. Adding RPMI support to U-Boot
does not take anything away from SCMI.
Platforms that use SCMI can continue to do so, and platforms
built on RPMI get the support they need.
So RPMI is not another interface that does the same thing. It is a
broader specification, developed openly by the community that uses
it in which you and anyone can also take part.
It wasn't my cover letter which described
"The goals and purpose of RPMI are similar to ARM's SCMI."
I am just saying that it looks like that you are creating parallel firmware
interface instead of extending/reusing existing one without really even trying
to talk to other vendors. I would prefer if we can work together on one spec and
extend it to cover both architectures.
When you have heterogeneous systems where you have mix of ARM and RISC-V cores
make no sense to have SCMI and RPMI servers both running to serve the same purpose.
Thanks,
Michal
