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Date:   Fri, 4 Sep 2020 14:00:44 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Qiu Wenbo <qiuwenbo@kylinos.com.cn>
Cc:     Anup Patel <anup@brainfault.org>,
        Christoph Hellwig <hch@infradead.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [GIT PULL] RISC-V Fixes for 5.9-rc2
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On Fri, Sep 04, 2020 at 08:58:25PM +0800, Qiu Wenbo wrote:
> I can confirm this patch also breaks K210 support. It seems that
> csr_read(CSR_TIME) will trigger an illegal instruction exception on K210.

CSR_TIME is trapped by just about every implementation I know (which is
explicitly allowed by the spec).  That is why we should never use it
from common M-mode code.