Re: Integrated MegaRAID controller and AMD IOMMU issue

From: Joerg Roedel
Date: Tue Jun 25 2013 - 05:35:49 EST


Hi James,

On Tue, Jun 25, 2013 at 12:12:53AM -0600, James Georgas wrote:
> I discussed the issue with an LSI engineer, and he said that since the
> integrated controller uses system memory, which it gets from the BIOS
> during initialization, there will be issues with the IOMMU. I assume
> he is referring to DMA address problems due to IOMMU translation.

Looks like the problem is in the LSI driver. The driver needs to dma-map
the system memory it gets from the BIOS (for example with dma_map_single)
and use the dma_handle returned for transactions. Otherwise the IOMMU
will block the accesses from the device and make it unusable.


Joerg


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