[microblaze-uclinux] Re: [PATCH 36/56] microblaze_v2: dma support

[Michal Simek <monstr@xxxxxxxxx>]

Hi all,

here is proposed struct.

struct scatterlist {
      dma_addr_t      	dma_address;
      unsigned long	page_link;
#ifdef CONFIG_DEBUG_SG
      unsigned long	sg_magic;
#endif
      unsigned int    	length;
      unsigned int    	offset;
};

Is it OK now?

Michal


>>> struct scatterlist {
>>>       unsigned long page_link;
>>>       unsigned int    offset;
>>>       unsigned int    length;
>>>       dma_addr_t      dma_address;
>>> };
>> If unsigned long is 32-bit but dma_addr_t is 64-bit, there may be a gap
>> between length and dma_address.
>>
> 
> But moving dma_address to the front only has the effect to create implicit
> padding at the end of struct scatterlist, so you don't gain anything
> either way.
> 
> It's only an internal definition that can be changed at any time without
> breaking applications, so I wouldn't worry about it, and better leave
> it identical to the other architectures.
> 
> The one thing that should indeed be changed is the addition of
> 'unsigned long sg_magic' that is needed for CONFIG_DEBUG_SG.
> 
> 	Arnd <><

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