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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Stefano Panella <stefano.panella@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: [Xen-devel] [PATCH 1/1] XEN: Use correct masking in xen_swiotlb_alloc_coherent.
Date: Wed, 5 Sep 2012 10:33:18 -0400	[thread overview]
Message-ID: <20120905143318.GA6908@phenom.dumpdata.com> (raw)
In-Reply-To: <50460B2E.3020200@citrix.com>

On Tue, Sep 04, 2012 at 03:07:42PM +0100, Stefano Panella wrote:
> On 08/31/2012 05:40 PM, Konrad Rzeszutek Wilk wrote:
> >On Fri, Aug 31, 2012 at 01:47:05PM +0100, David Vrabel wrote:
> >>On 31/08/12 10:57, Stefano Panella wrote:
> >>>When running 32-bit pvops-dom0 and a driver tries to allocate a coherent
> >>>DMA-memory the xen swiotlb-implementation returned memory beyond 4GB.
> >>>
> >>>This caused for example not working sound on a system with 4 GB and a 64-bit
> >>>compatible sound-card with sets the DMA-mask to 64bit.
> >>>
> >>>On bare-metal and the forward-ported xen-dom0 patches from OpenSuse a coherent
> >>>DMA-memory is always allocated inside the 32-bit address-range by calling
> >>>dma_alloc_coherent_mask.
> >>We should have the same behaviour under Xen as bare metal so:
> >>
> >>Acked-By: David Vrabel <david.vrabel@citrix.com>
> >>
> >>This does limit the DMA mask to 32-bits by passing it through an
> >>unsigned long, which seems a bit sneaky...
> >so is the issue that we are not casting it from 'u64' to 'u32'
> >(unsigned long) on 32-bit?
> 
> Yes. I do not completely understand why but I think on 32-bit kernel we need to cast dma_mask to u32. This is done automatically using dma_alloc_coherent_mask()

OK, patch applied. I altered the git commit description a bit and
changed the author to  Ronny Hegewald <ronny.hegewald@online.de>.

Also added it on stable@vger.kernel.org

Thanks for tracking this down.

      parent reply	other threads:[~2012-09-05 14:43 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-31  9:57 Stefano Panella
2012-08-31 12:47 ` [Xen-devel] " David Vrabel
2012-08-31 16:40   ` Konrad Rzeszutek Wilk
2012-09-04 14:07     ` Stefano Panella
2012-09-04 14:37       ` Konrad Rzeszutek Wilk
2012-09-04 14:55         ` David Vrabel
2012-09-04 15:12           ` Stefano Panella
2012-09-04 16:44             ` David Vrabel
2012-09-04 16:40               ` Konrad Rzeszutek Wilk
2012-09-05 13:13                 ` Stefano Panella
2012-09-05 14:33       ` Konrad Rzeszutek Wilk [this message]

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