Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Sun, 11 Nov 2018 14:14:12 -0800 (PST)
Subject:     Re: [PATCH] riscv: add S and U modes to ISA string
In-Reply-To: <7958aa50-8808-e909-753c-e232b3d1f84e@packi.ch>
CC:     david.abdurachmanov@gmail.com, aou@eecs.berkeley.edu,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
From:   Palmer Dabbelt <palmer@sifive.com>
To:     me@packi.ch
Message-ID: <mhng-58f419dd-47a6-4540-91b6-08be173d4216@palmer-si-x1c4>
Mime-Version: 1.0 (MHng)
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sat, 10 Nov 2018 00:35:15 PST (-0800), me@packi.ch wrote:
> On 10.11.18 07:45, David Abdurachmanov wrote:
>>
>> The patch adds the missing S and U modes.
>
> This is the same patch I submitted earlier (see v2 here [1], based on
> Palmer's feedback). Palmer stated that the "S" extension should not be
> exposed to usermode.
>
> Since two people arrived at the same solution, I wonder if the
> supervisor mode should really be hidden from userspace, as it's about
> the CPU information, not about the environment the calling code is
> running as.
>
> [1] https://lkml.org/lkml/2018/11/10/96

I still think S should be hidden from applications.  This patch was fairly 
mechanical, so it probably just wasn't though about twice -- that's the problem 
with user ABI stuff, lots of times the obvious answer isn't the correct one :).

I'll take your second patch, I just haven't gotten around to actually fully 
reviewing patches yet as I'm still in my email triage phase.

Thanks!