netdev - Re: [PATCH net] idpf: avoid compiler padding in virtchnl2

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Date: Tue, 23 Jan 2024 09:57:28 -0800
From: "Linga, Pavan Kumar" <pavan.kumar.linga@...el.com>
To: David Laight <David.Laight@...LAB.COM>, 'Tony Nguyen'
	<anthony.l.nguyen@...el.com>, "davem@...emloft.net" <davem@...emloft.net>,
	"kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>
CC: "willemb@...gle.com" <willemb@...gle.com>, kernel test robot
	<lkp@...el.com>, Przemek Kitszel <przemyslaw.kitszel@...el.com>, Paul Menzel
	<pmenzel@...gen.mpg.de>, Simon Horman <horms@...nel.org>, Krishneil Singh
	<krishneil.k.singh@...el.com>
Subject: Re: [PATCH net] idpf: avoid compiler padding in virtchnl2_ptype
 struct



On 1/22/2024 3:01 PM, David Laight wrote:
> From: Tony Nguyen
>> Sent: 22 January 2024 17:52
>>
>> In the arm random config file, kconfig option 'CONFIG_AEABI' is
>> disabled which results in adding the compiler flag '-mabi=apcs-gnu'.
> 
> Isn't the arm EABI pretty much the only value used for the last
> 15 years at least?
> Doesn't it also change the size of enums?
> 
> So perhaps it shouldn't be possible to unset it?
> 

Thanks for the review. The following is the only warning reported by the 
LKP with the random config file and I am not sure why this option was 
not set. When I set CONFIG_AEABI, the compiler flag changed to 
'mabi=aapcs-linux' and this issue was not seen.


>> This causes the compiler to add padding in virtchnl2_ptype
>> structure to align it to 8 bytes, resulting in the following
>> size check failure:
>>
>> include/linux/build_bug.h:78:41: error: static assertion failed: "(6) == sizeof(struct
>> virtchnl2_ptype)"
> 
> And turn that conditional the correct way around...
> 

Sure, will do that.

Thanks,
Pavan

> 	David
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
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