Re: [PATCH] drivers/ata: Add the SW NCQ support to sata_nv for MCP51/MCP55/MCP61

[Jeff Garzik]

Alan Cox wrote:
> > That shouldn't be a problem, libata default DMA mask is 32 bits (which 
> > isn't overridden with this controller) and so the block layer will 
> > bounce any data being read/written above that point with IOMMU or 
> > swiotlb. The comment is a bit unnecessarily scary.
>
> Adding a BUG_ON for this would be wise. Its trivial to check and a BUG
> rather than corruption if this assumption ever changes would be far
> preferable

The default DMA mask -everywhere- is 32 bits.

A lot of code will break if this assumption ever changes, not just libata.

	Jeff



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