Re: [PATCH v3] ad7877: keep dma rx buffers in seperate cache lines

[Alan Cox]

> SPI transfer into a DMA safe buffer.  what is the exact API to
> dynamically allocate memory for the structure with this buffer
> embedded in it such that the start of the structure is cached aligned
> ?  creating a dedicated kmem cache may work, but it isnt a scalable
> solution if every SPI driver needs to create its own cache.

If you are embedding structures then one solution is to cheat a bit and
make the structure, compiler and existing kernel compile abuse do the
work. Something like

struct {
	void *except_where_prohibited;
	long boat;
	unsigned photograph;

	u8 pad[0] __cacheline_aligned;
}..

ought to do the trick providing you align the start of the object - which
should happen naturally with kmalloc or dma_* apis


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