Re: Platform specification questions

Kumar Sankaran

On Mon, Dec 13, 2021 at 8:30 AM Anup Patel <anup@...> wrote:

On Mon, Dec 13, 2021 at 6:46 PM Ved Shanbhogue <ved@...> wrote:

Hi Anup
On Mon, Dec 13, 2021 at 09:25:43AM +0530, Anup Patel wrote:

"Software interrupts for M-mode, HS-mode and VS-mode are supported using AIA IMSIC devices". Is the term "software interrupt" here intended to be the minor identities 3, 1, and 2? If so please clarify what the support in IMSIC is expected to be for these minor identities.
I think the confusion here is because the RISC-V platform
specification uses the term "software interrupt" for both
"inter-processor interrupt" and "minor identities 3, 1, and 2". I
suggest using the term "inter-processor interrupt" at most places and
only use the term "software interrupt" in-context of ACLINT MSWI or
SSWI devices.
Yes, that was my conclusion that "software interrupt" here was used to mean an IPI. I think clearing this up would be helpful.

Is supporting SBI TIME optional if the server extension is supported as server extension requires Sstc? Is supporting SBI IPI optional if AiA IMSIC is supported?
I agree, this text needs to be improved because now Base and Server
are separate platforms. Since, the Server platform mandates IMSIC and
Priv Sstc extension so SBI TIME, IPI and RFENCE can be optional but
this is not true for the Base platform.
Yes, however the Server is additived to the base as written. Even for base, if Sstc and IMSIC are supported then SBI TIME, IPI, and RFENCE can be optional.
The current text/organization is going to change (as discussed in
previous meetings). The Server platform will be a separate platform
independent of the Base platform because some of the requirements will
be different for both platforms. (@Kumar/Atish please add if I missed
Yes, as per our agreement during the Platform HSC meeting several
weeks back, the plan is to make the OS-A Embedded and OS-A Server as
individual platforms without any relationship to each other.
Common requirements between OS-A Embedded and OS-A Server will be put
into a new section called OS-A Common Requirements. This way, we can
have separate requirements for each platform independent of the other.
So the OS-A Server will NOT be an extension of OS-A Embedded anymore
but a separate platform.

For the Base platform, I agree we can make SBI TIME, IPI and RFENCE
mandatory only when IMSIC and Sstc is not present. (@Atish do you
recall any other rationale in this context ?)




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