linux-kernel - Re: [PATCH v10 04/10] arm64/sysreg: Add a comment that the sysreg file should be sorted

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Message-ID: <b4082b98-e234-4825-9935-971a630f438b@linaro.org>
Date: Wed, 15 Jan 2025 10:43:07 +0000
From: James Clark <james.clark@...aro.org>
To: Rob Herring <robh@...nel.org>, Marc Zyngier <maz@...nel.org>,
 Mark Brown <broonie@...nel.org>
Cc: kvmarm@...ts.linux.dev, oliver.upton@...ux.dev, suzuki.poulose@....com,
 coresight@...ts.linaro.org, James Clark <james.clark@....com>,
 Joey Gouly <joey.gouly@....com>, Zenghui Yu <yuzenghui@...wei.com>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 Mike Leach <mike.leach@...aro.org>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Mark Rutland <mark.rutland@....com>,
 Anshuman Khandual <anshuman.khandual@....com>,
 Shiqi Liu <shiqiliu@...t.edu.cn>, James Morse <james.morse@....com>,
 Fuad Tabba <tabba@...gle.com>, Raghavendra Rao Ananta <rananta@...gle.com>,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 04/10] arm64/sysreg: Add a comment that the sysreg
 file should be sorted



On 14/01/2025 6:16 pm, Rob Herring wrote:
> On Mon, Jan 13, 2025 at 10:49 AM Marc Zyngier <maz@...nel.org> wrote:
>>
>> On Mon, 13 Jan 2025 15:43:39 +0000,
>> James Clark <james.clark@...aro.org> wrote:
>>>
>>>
>>>
>>> On 12/01/2025 12:49 pm, Marc Zyngier wrote:
>>>> On Tue, 07 Jan 2025 11:32:41 +0000,
>>>> James Clark <james.clark@...aro.org> wrote:
>>>>>
>>>>> From: James Clark <james.clark@....com>
>>>>>
>>>>> There are a few entries particularly at the end of the file that aren't
>>>>> in order. To avoid confusion, add a comment that might help new entries
>>>>> to be added in the right place.
>>>>>
>>>>> Reviewed-by: Mark Brown <broonie@...nel.org>
>>>>> Signed-off-by: James Clark <james.clark@....com>
>>>>> Signed-off-by: James Clark <james.clark@...aro.org>
>>>>> ---
>>>>>    arch/arm64/tools/sysreg | 2 ++
>>>>>    1 file changed, 2 insertions(+)
>>>>>
>>>>> diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
>>>>> index b081b54d6d22..4ba167089e2a 100644
>>>>> --- a/arch/arm64/tools/sysreg
>>>>> +++ b/arch/arm64/tools/sysreg
>>>>> @@ -48,6 +48,8 @@
>>>>>    # feature that introduces them (eg, FEAT_LS64_ACCDATA introduces enumeration
>>>>>    # item ACCDATA) though it may be more taseful to do something else.
>>>>>    +# Please try to keep entries in this file sorted by sysreg
>>>>> encoding.
>>>>> +
>>>>>    Sysreg   OSDTRRX_EL1     2       0       0       0       2
>>>>>    Res0     63:32
>>>>>    Field    31:0    DTRRX
>>>>
>>>> "Do as I say, don't do as I do".
>>>>
>>>> I don't think this makes any sense if we don't actually sort the file
>>>> the first place.
>>>>
>>>>      M.
>>>>
>>>
>>> I think it's ok if it avoids review comments that new entries should
>>> be sorted. Or maybe we do the opposite and the comment should say this
>>> file is allowed to be unsorted...
>>
>> The better option would be to add the comment *and* sort the file.
>> Leading by example has some value, it seems.
> 
> IME, it's better if documentation just states what the tools enforce.
> 
> Can't we add something like this to the header generation:
> 
> $ grep '^Sysreg\s' arch/arm64/tools/sysreg | sort -n -k3 -k4 -k5 -k6 -k7 -c
> sort: -:22: disorder: Sysreg ID_MMFR4_EL1       3       0       0
>   2       6
> 
> Rob

Actually I updated gen-sysreg.awk to fail the build if it's not sorted, 
was just about to post it. I don't know if a build failure or a warning 
is preferred but I can do either.

James