Re: [Xen-devel] [PATCH 1/1] XEN: Use correct masking in xen_swiotlb_alloc_coherent.

From: Stefano Panella
Date: Tue Sep 04 2012 - 11:12:24 EST


On 09/04/2012 03:55 PM, David Vrabel wrote:
On 04/09/12 15:37, Konrad Rzeszutek Wilk wrote:
On Tue, Sep 04, 2012 at 03:07:42PM +0100, Stefano Panella wrote:
So if hwdev->coherent_dma_mask is set to 0xffffffffffffffff our dma_mask will
be u64 set to 0xffffffffffffffff even if we set it to DMA_BIT_MASK(32) previously.
That is what I was missing. Let me include that in the git commit and also
put this patch on the stable tree.
Note that this appears to be a work around for a bug in the sound system
or Intel HDA device driver which is incorrectly truncating a dma_addr_t
to a u32. So by ensuring a DMA_BIT_MASK(32) when the dma_addr_t is
truncated it still works.

David
Sorry David, I am not completely sure I understand your argument in favour of a bug in the
sound system or Intel HDA device driver. Could you please elaborate more in detail about this?

Thanks,

Stefano
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