Re: [tech-aia] RISC-V ACLINT specification is now hosted on RISC-V GitHub


Anup Patel
 

Hi Neel,

 

You first question is already answered by Greg.

 

Regarding second question/suggestion, I agree we should explicitly state how to disable a pending interrupt.

 

Regards,

Anup

 

From: tech-unixplatformspec@... <tech-unixplatformspec@...> On Behalf Of Neel Gala
Sent: 27 May 2021 23:05
To: Anup Patel <Anup.Patel@...>
Cc: Josh Scheid <jscheid@...>; tech-aia@...; tech-unixplatformspec@...; Atish Patra <Atish.Patra@...>; Greg Favor <gfavor@...>; Alistair Francis <Alistair.Francis@...>; Andrew Waterman <andrew@...>; John Hauser <jh.riscv@...>
Subject: Re: [RISC-V] [tech-unixplatformspec] [tech-aia] RISC-V ACLINT specification is now hosted on RISC-V GitHub

 

Hi,

 

Minor comments:

 

Should there be a mention that the user level "time" csr (0xC01) which is used by the rdtime pseudo-instruction will enable a read-only peek into the mtime register? Would this require change in Table-1 privilege mode accesses? as well?

 

Should there also be a suggestion/recommendation on how to disable a pending interrupt (typically by writing to mtimecmp)?

 

On Thu, May 27, 2021 at 10:45 AM Anup Patel <anup.patel@...> wrote:

Hi Josh,

 

I have created a GitHub PR addressing your comments. Please check if you are okay with this.

https://github.com/riscv/riscv-aclint/pull/2

 

Regards,

Anup

 

From: tech-aia@... <tech-aia@...> On Behalf Of Josh Scheid
Sent: 27 May 2021 01:58
To: Anup Patel <Anup.Patel@...>
Cc: tech-aia@...; tech-unixplatformspec@...; Atish Patra <Atish.Patra@...>; Greg Favor <gfavor@...>; Alistair Francis <Alistair.Francis@...>; Andrew Waterman <andrew@...>; John Hauser <jh.riscv@...>
Subject: Re: [tech-aia] RISC-V ACLINT specification is now hosted on RISC-V GitHub

 

Thanks for writing this up, Anup.

 

In https://github.com/riscv/riscv-aclint/blob/master/riscv-aclint.adoc#24-synchronizing-multiple-mtimer-devices, the SW algorithm should include verifying the reference-target delta, retrying if the delta is out of bounds, and / or reporting failure to verify the synchronization is in bounds.

 

-Josh

 

 

On Tue, May 25, 2021 at 10:18 PM Anup Patel <anup.patel@...> wrote:

Hi All,

The RISC-V ACLINT specification is now hosted on RISC-V GitHub page:
https://github.com/riscv/riscv-aclint
https://github.com/riscv/riscv-aclint/blob/master/riscv-aclint.adoc

Please review this at your end send feedback on AIA/Platform mailing
lists.

The RISC-V ACLINT specification is intended to be small and backward
compatible to the SiFive CLINT specification which makes existing
RISC-V platforms compliant with the RISC-V ACLINT specification.

Overall, from platforms specification perspective it complements
the RISC-V AIA specification by providing IPI and Timer functionality.

A complete functional implementation is available for QEMU RISC-V
along with OpenSBI and Linux RISC-V changes. Please refer, the
riscv_aclint_v1 branch in following repos:
https://github.com/avpatel/qemu.git
https://github.com/avpatel/opensbi.git
https://github.com/avpatel/linux.git

To enable ACLINT emulation on QEMU, use "-M virt,aclint=on"
instead of just "-M virt" in your QEMU command line. For now,
QEMU supports ACLINT only for virt machine.

Regards,
Anup






 

--

Neel Gala

 

Join tech-unixplatformspec@lists.riscv.org to automatically receive all group messages.