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Re: [PATCH 1/1] target/riscv: fix VS interrupts forwarding to HS


From: Jose Martins
Subject: Re: [PATCH 1/1] target/riscv: fix VS interrupts forwarding to HS
Date: Fri, 1 May 2020 19:56:48 +0100

Reached out to Andrew Waterman. This was his response:

"I think the encoding of the privileged modes is a red herring.  HS is
inherently more privileged than VS, since it controls memory
protection and interrupt delegation for VS.
Certainly the intent is that HS-mode interrupts are always enabled
while executing in VS-mode.  Otherwise, badly behaved VS-mode software
could starve HS-mode of interrupts."

So my assumption was correct.

Jose

On Thu, 30 Apr 2020 at 22:47, Jose Martins <address@hidden> wrote:
>
> > I'm not sure HS is a higher privilege mode.
> >
> > HS is privilege encoding 1, which is the same as VS (VU is obviously lower).
>
> I just checked the spec and it doesn't actually, explicitly state that
> HS is a higher-privilege mode than VS. I thought this was something
> implicit, but you might be right. I'll try to reach out to the spec
> authors to clarify this.
>
> Jose



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