Re: [RFC 0/2] RISC-V: A proposal to add vendor-specific code

From: Alan Kao
Date: Wed Oct 31 2018 - 20:55:55 EST


On Wed, Oct 31, 2018 at 07:17:45AM -0700, Christoph Hellwig wrote:
> On Wed, Oct 31, 2018 at 04:46:10PM +0530, Anup Patel wrote:
> > I agree that we need a place for vendor-specific ISA extensions and
> > having vendor-specific directories is also good.
>
> The only sensible answer is that we should not allow vendor specific
> extensions in the kernel at all. ...

How can this even be possible if a extension includes an extra register
set as some domain-specific context? In such a case, kernel should
at least process the context during any context switch, just like how it
deals with the FP context.

> ... We need to standardize cache flushing
> and we need to do it soon and not introduce horrible bandaids because
> the foundation did not do its work.
>
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