> No dia 7 de out. de 2022, às 18:58, Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx> escreveu:
>
> Hi Devendra,
>
> Quoting Devendra Tewari (2022-04-22 20:20:31)
>> Fixes clang warning: field within 'v4l2_ext_control' is less than
>
> Can you detail which version of clang this occurs with? Have you tried
> more than one version?
>
This started happening with version 14.0.1 and I continue to see it with version 15.
>
>> 'v4l2_ext_control::(anonymous union
>>
>> Signed-off-by: Devendra Tewari <devendra.tewari@xxxxxxxxx>
>> ---
>> include/uapi/linux/videodev2.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>> index 3768a0a80830..767c52c722cd 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -1765,7 +1765,7 @@ struct v4l2_ext_control {
>> struct v4l2_ctrl_vp9_compressed_hdr __user *p_vp9_compressed_hdr_probs;
>> struct v4l2_ctrl_vp9_frame __user *p_vp9_frame;
>> void __user *ptr;
>> - };
>> + } __attribute__ ((packed));
>
> This is a curious fix. It's applying a packed attribute to the union,
> which I presume means that it's then applying the packed attribute to
> any item in the union.
>
> The items are all either: __s32, __s64, values - or pointers.
>
> While applying this attribute here may fix the compiler warning, I'm not
> sure it's clear why this is required. This file also has other
> locations where a union inside a packed struct is not marked as packed.
> Should all unions be marked with the attribute?
Interesting - I need to look deeper into packed.
> Is there any more context from the compiler warning beyond what is
> reported above?
I'll post a more detailed log asap.
>
> --
> Kieran
>
>
>> } __attribute__ ((packed));
>>
>> struct v4l2_ext_controls {
>> --
>> 2.25.1
>>
Thanks,
Devendra
