Re: Question about iommu on x86_64 and radeon driver.

From: Daniel Haid
Date: Tue May 31 2011 - 15:57:45 EST


Just another question, the problem seems to be an issue with

swiotlb=force

and I assume that without "force" DMA with addresses that
already are below 4GB should be handled without any
bounce-buffer, and with "force" everything goes through
the bounce-buffer, is this correct?

Now I have a VIA chipset where the IOMMU does not work, so
swiotlb is activated, but is it activated in force mode or
in normal mode? How can I find out?

If it is activated in force mode, maybe the problem will
go away in normal mode?

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