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Date:   Thu, 1 Nov 2018 08:55:42 +0800
From:   Alan Kao <alankao@andestech.com>
To:     Christoph Hellwig <hch@infradead.org>
CC:     Anup Patel <anup@brainfault.org>, Zong Li <zong@andestech.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Arnd Bergmann <arnd@arndb.de>, <greentime@andestech.com>,
        Palmer Dabbelt <palmer@sifive.com>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        <vincentc@andestech.com>, <linux-riscv@lists.infradead.org>,
        <deanbo422@gmail.com>
Subject: Re: [RFC 0/2] RISC-V: A proposal to add vendor-specific code
Message-ID: <20181101005541.GA25604@andestech.com>
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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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