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From:   Jonathan Corbet <corbet@lwn.net>
To:     Palmer Dabbelt <palmer@dabbelt.com>,
        Conor Dooley <conor.dooley@microchip.com>
Cc:     Conor Dooley <conor.dooley@microchip.com>,
        linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Documentation: riscv: note that counter access is part
 of the uABI
In-Reply-To: <mhng-72f383f6-a85f-4587-9fa6-f85fb9f27ec8@palmer-ri-x1c9a>
References: <mhng-72f383f6-a85f-4587-9fa6-f85fb9f27ec8@palmer-ri-x1c9a>
Date:   Sat, 03 Dec 2022 03:38:49 -0700
Message-ID: <87359wpy9y.fsf@meer.lwn.net>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Palmer Dabbelt <palmer@dabbelt.com> writes:

> On Thu, 01 Dec 2022 05:51:10 PST (-0800), Conor Dooley wrote:
>> Commit 5a5294fbe020 ("RISC-V: Re-enable counter access from userspace")
>> fixed userspace access to CYCLE, TIME & INSTRET counters and left a nice
>> comment in-place about why they must not be restricted. Since we now
>> have a uABI doc in RISC-V land, add a section documenting it.
>>
>> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
>> ---
>> Based on an, as yet, unsent v2 of my other uABI changes. I don't expect
>> it to be applicable, just getting a patch into patchwork while I don't
>> forget about this.
>> ---
>>  Documentation/riscv/uabi.rst | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/Documentation/riscv/uabi.rst b/Documentation/riscv/uabi.rst
>> index 8d2651e42fda..638ddce56700 100644
>> --- a/Documentation/riscv/uabi.rst
>> +++ b/Documentation/riscv/uabi.rst
>> @@ -3,6 +3,13 @@
>>  RISC-V Linux User ABI
>>  =====================
>>
>> +Counter access
>> +--------------
>> +
>> +Access to the CYCLE, TIME and INSTRET counters, now controlled by the SBI PMU
>> +extension, were part of the ISA when the uABI was frozen & so remain accessible
>> +from userspace.
>> +
>>  ISA string ordering in /proc/cpuinfo
>>  ------------------------------------
>>
>>
>> base-commit: 13ee7ef407cfcf63f4f047460ac5bb6ba5a3447d
>> prerequisite-patch-id: d17a9ffb6fcf99eb683728da98cd50e18cd28fe8
>> prerequisite-patch-id: 0df4127e3f4a0c02a235fea00bcb69cd94fabb38
>> prerequisite-patch-id: 171724b870ba212b714ebbded480269accd83733
>
> Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
> Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
>
> I think I merged the last one of these, but if the doc folks pick it up 
> that's fine with me.  Otherwise I'll take it when it comes back around, 
> so folks have time to take a look.

"Doc folks" applied it, thanks. :)

jon