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Date: Thu, 16 Aug 2018 09:44:36 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>,
 linuxppc-dev <linuxppc-dev@ozlabs.org>,
 Laurent Dufour <ldufour@linux.vnet.ibm.com>,
 Michal Suchanek <msuchanek@suse.com>,
 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
 Nicholas Piggin <npiggin@gmail.com>, Ananth Narayan <ananth@in.ibm.com>
Subject: Re: [PATCH v7 4/9] powerpc/pseries: Define MCE error event section.
Message-ID: <20180816144435.GZ31204@gate.crashing.org>
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Hi!

On Thu, Aug 16, 2018 at 02:14:39PM +1000, Michael Ellerman wrote:
> Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com> writes:
> > On 08/08/2018 08:12 PM, Michael Ellerman wrote:
> >>> +			uint8_t	reserved_1[6];
> >>> +			__be64	effective_address;
> >>> +			__be64	logical_address;
> >>> +		} ue_error;
> >>> +		struct {
> >>> +			uint8_t	soft_err_type;
> >>> +			/* XXXXXXXX
> >>> +			 * X		1: Effective address provided.
> >>> +			 *  XXXXX	5: Reserved.
> >>> +			 *       XX	2: Type of SLB/ERAT/TLB error.
> >>> +			 */
> >>> +			uint8_t	reserved_1[6];
> >>> +			__be64	effective_address;
> >>> +			uint8_t	reserved_2[8];
> >>> +		} soft_error;
> >>> +	} u;
> >>> +};
> >>> +#pragma pack(pop)
> >> 
> >> Why not __packed ?
> >
> > Because when used __packed it added 1 byte extra padding between
> > reserved_1[6] and effective_address. That caused wrong effective address
> > to be printed on the console. Hence I switched to #pragma pack to force
> > 1 byte alignment for this structure alone.
> 
> OK, that's weird.

Yes, if that is true, then please open a GCC bugzilla report.


Segher