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Request a new CSR address for pmp ext.


Joe Xie
 

Hi unpriv. Standing Committee

 

The TEE group is working on a PMP extension proposal to enhance PMP security, see https://docs.google.com/document/d/1Mh_aiHYxemL0umN3GTTw8vsbmzHZ_nxZXgjgOUzbvc8/edit?usp=sharing for details. The proposal is approved by TEE group.

 

The proposal requires to add a new machine mode CSR (called MSECCFG), we had offline discussion with Andrew before and currently the proposal is using 0x390. I just learned that the new policy requires an official approval from standing committee.

 

I am writing this email to ask approval for adding a new CSR, preferably we would like to use 0x390 but we are open to suggestions. Can you kindly review the proposal and assign a new CSR?

 

Thanks!


Ken Dockser
 

Hi Joe,

 

I am in the process of updating the proposed  Instruction Encoding Allocation policy to include proposed new state. We have not yet determined how we will go about reviewing such proposals in the unprivileged standing committee. That said, we need to do this soon as yours is the first of many proposals for instructions/state that are headed our way.

 

Thanks for providing a pointer to your proposal, I will review it and discuss it with the other members on the unprivileged standing committee. I’ll let you know if we have any questions, concerns or need more information. My plan is to get back to you within two weeks (i.e., by October 21).

 

Thanks,

Ken

 

From: tech-unprivileged@... <tech-unprivileged@...> On Behalf Of Joe Xie
Sent: Tuesday, October 6, 2020 10:27 PM
To: tech-unprivileged@...
Cc: Andrew Waterman <andrew@...>; Nick Kossifidis <mick@...>; tech-tee@...
Subject: [RISC-V] [tech-unprivileged] Request a new CSR address for pmp ext.

 

CAUTION: This email originated from outside of the organization.

Hi unpriv. Standing Committee

 

The TEE group is working on a PMP extension proposal to enhance PMP security, see https://docs.google.com/document/d/1Mh_aiHYxemL0umN3GTTw8vsbmzHZ_nxZXgjgOUzbvc8/edit?usp=sharing for details. The proposal is approved by TEE group.

 

The proposal requires to add a new machine mode CSR (called MSECCFG), we had offline discussion with Andrew before and currently the proposal is using 0x390. I just learned that the new policy requires an official approval from standing committee.

 

I am writing this email to ask approval for adding a new CSR, preferably we would like to use 0x390 but we are open to suggestions. Can you kindly review the proposal and assign a new CSR?

 

Thanks!


Chuanhua Chang
 

We do not have an approval process for the new CSR number allocation yet.

But personally, I do not see any problem with using 0x390 as the CSR number for MSECCFG, especially it has been discussed in the TEE TG with careful considerations and Andrew was in the discussion loop.

Regards,
Chuanhua


Ken Dockser
 

Thanks Chuanhua.

 

My fellow unprivileged members,

 

The allocation of CSRs is included in the instruction encoding allocation policy (which clearly needs a new name). This process is intended to not only make fair and  rational decisions about new state and instruction encodings, but also as a means to pre-screen proposals to ensure that they are in the best interest of the RISC-V. Basically, we need to ensure that what is proposed fits in well with the existing architecture and philosophy, will have a positive impact on the RISC-V architecture, and will not negatively impact it’s long term viability. We need to avoid decisions that will set precedents that lead to unintended consequences.

 

In order for proposals to be able to progress towards public review we need to set up an approval process that applies this policy. This includes:

  1. A standard means for applicants to submit their requests for approval
  2. A means for tracking the requests
  3. A subcommittee comprised of unprivileged standing committee members who will commit reviewing the proposals in the context of the policy and provide timely feedback.
  4. A means to come to a consensus on approval and/or feedback for the proposal.

 

The tricky part is the subcommittee. I am happy to chair it, but we need others with the appropriate expertise and who can commit to putting in the time. Any takers?

 

Thanks,

Ken

 

From: Chuanhua Chang <chchang@...>
Sent: Thursday, October 15, 2020 4:21 AM
To: Ken Dockser <kdockser@...>; tech-unprivileged@...
Subject: Re: [RISC-V] [tech-unprivileged] Request a new CSR address for pmp ext.

 

CAUTION: This email originated from outside of the organization.

We do not have an approval process for the new CSR number allocation yet.

But personally, I do not see any problem with using 0x390 as the CSR number for MSECCFG, especially it has been discussed in the TEE TG with careful considerations and Andrew was in the discussion loop.

Regards,
Chuanhua