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Date: Fri, 9 Mar 2012 22:19:14 +1100
From: David Gibson <david@gibson.dropbear.id.au>
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Subject: Re: [Qemu-devel] [PATCH 05/13] iommu: Add universal DMA helper
	functions
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: mst@redhat.com, Joerg Rodel <Joerg.Rodel@amd.com>, agraf@suse.de, qemu-devel@nongnu.org, eduard.munteanu@linux360.ro, rth@twiddle.net

On Fri, Mar 09, 2012 at 11:06:41AM +0100, Paolo Bonzini wrote:
> Il 09/03/2012 06:01, David Gibson ha scritto:
> > +static inline int dma_memory_read(DMAContext *dma, dma_addr_t addr,
> > +                                  void *buf, dma_addr_t len)
> > +{
> > +    return dma_memory_rw(dma, addr, buf, len, DMA_DIRECTION_TO_DEVICE);
> > +}
> > +
> > +static inline int dma_memory_write(DMAContext *dma, dma_addr_t addr,
> > +                                   const void *buf, dma_addr_t len)
> > +{
> > +    return dma_memory_rw(dma, addr, (void *)buf, len,
> > +                         DMA_DIRECTION_FROM_DEVICE);
> > +}
> 
> This is opposite to the convention of dma_buf_read/dma_buf_write, which
> is from the point of view of the device.

Uh, these are from the point of view of the device - the device writes
to memory == transfer from device.  More importantly, this is the same
convention as cpu_physical_memory_{read,write}() which is what these
generally replace.  dma_buf_read() is from the point of view of the
core/memory.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson