linux-kernel - Re: [PATCH v2 1/1] arm64: rsi: Add automatic arm-cca-guest module loading

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Message-ID: <a64a21cc-6d10-4e8f-9ab9-87aca44ca858@arm.com>
Date: Tue, 3 Dec 2024 09:30:43 -0600
From: Jeremy Linton <jeremy.linton@....com>
To: Gavin Shan <gshan@...hat.com>, kernel test robot <lkp@...el.com>,
 linux-arm-kernel@...ts.infradead.org
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
 steven.price@....com, sami.mujawar@....com, suzuki.poulose@....com,
 will@...nel.org, catalin.marinas@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/1] arm64: rsi: Add automatic arm-cca-guest module
 loading

On 12/3/24 2:56 AM, Gavin Shan wrote:
> 
> 
> On 12/3/24 4:03 PM, kernel test robot wrote:
>> Hi Jeremy,
>>
>> kernel test robot noticed the following build warnings:
>>
>> [auto build test WARNING on arm64/for-next/core]
>> [also build test WARNING on linus/master v6.13-rc1 next-20241128]
>> [cannot apply to kvmarm/next soc/for-next arm/for-next arm/fixes]
>> [If your patch is applied to the wrong git tree, kindly drop us a note.
>> And when submitting patch, we suggest to use '--base' as documented in
>> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>>
>> url:    https://github.com/intel-lab-lkp/linux/commits/Jeremy-Linton/ 
>> arm64-rsi-Add-automatic-arm-cca-guest-module-loading/20241203-080347
>> base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/ 
>> linux.git for-next/core
>> patch link:    https://lore.kernel.org/r/20241203000156.72451-2- 
>> jeremy.linton%40arm.com
>> patch subject: [PATCH v2 1/1] arm64: rsi: Add automatic arm-cca-guest 
>> module loading
>> config: arm64-randconfig-004-20241203 (https://download.01.org/0day- 
>> ci/archive/20241203/202412031348.bp5i3ws2-lkp@...el.com/config)
>> compiler: clang version 20.0.0git (https://github.com/llvm/llvm- 
>> project 592c0fe55f6d9a811028b5f3507be91458ab2713)
>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/ 
>> archive/20241203/202412031348.bp5i3ws2-lkp@...el.com/reproduce)
>>
>> If you fix the issue in a separate patch/commit (i.e. not just a new 
>> version of
>> the same patch/commit), kindly add following tags
>> | Reported-by: kernel test robot <lkp@...el.com>
>> | Closes: https://lore.kernel.org/oe-kbuild-all/202412031348.bp5i3ws2- 
>> lkp@...el.com/
>>
>> All warnings (new ones prefixed by >>):
>>
>>>> drivers/virt/coco/arm-cca-guest/arm-cca-guest.c:224:21: warning: 
>>>> attribute declaration must precede definition [-Wignored-attributes]
>>       224 | static const struct __maybe_unused platform_device_id 
>> arm_cca_match[] = {
>>           |                     ^
>>     include/linux/compiler_attributes.h:356:56: note: expanded from 
>> macro '__maybe_unused'
>>       356 | #define __maybe_unused                  
>> __attribute__((__unused__))
>>           |                                                        ^
>>     include/linux/mod_devicetable.h:607:8: note: previous definition 
>> is here
>>       607 | struct platform_device_id {
>>           |        ^
>>>> drivers/virt/coco/arm-cca-guest/arm-cca-guest.c:224:55: warning: 
>>>> unused variable 'arm_cca_match' [-Wunused-const-variable]
>>       224 | static const struct __maybe_unused platform_device_id 
>> arm_cca_match[] = {
>>           |                                                       
>> ^~~~~~~~~~~~~
>>     2 warnings generated.
>>
>>
>> vim +224 drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
>>
>>     222
>>     223    /* modalias, so userspace can autoload this module when RSI 
>> is available */
>>   > 224    static const struct __maybe_unused platform_device_id 
>> arm_cca_match[] = {
>>     225        { RSI_PDEV_NAME, 0},
>>     226        { }
>>     227    };
>>     228
>>
> 
> The definition may have to be something like below, to avoid the 
> compiling warning.
> 
> static const struct platform_device_id __maybe_unused arm_cca_match[] = {

I should have tested this with clang rather than copy/pasting the 
utilization from somewhere else! It looks like a number of other kernel 
users are putting it before the '=', but its sorta annoying because it 
seems like the kind of warning that should be suppressed globally for 
this case (module device description in module that can be built in).



>         ...
> };
> 
> Thanks,
> Gavin
>