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Sender: Eduard - Gabriel Munteanu <edgmnt@gmail.com>
Date: Thu, 2 Sep 2010 11:51:04 +0300
From: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Subject: Re: [Qemu-devel] [PATCH 2/7] pci: memory access API and IOMMU support
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To: Stefan Weil <weil@mail.berlios.de>
Cc: kvm@vger.kernel.org, mst@redhat.com, joro@8bytes.org, qemu-devel@nongnu.org, blauwirbel@gmail.com, yamahata@valinux.co.jp, paul@codesourcery.com, avi@redhat.com

On Wed, Sep 01, 2010 at 10:10:30PM +0200, Stefan Weil wrote:
> Please see my comments at the end of this mail.
> 
> 
> Am 30.08.2010 00:08, schrieb Eduard - Gabriel Munteanu:
> > PCI devices should access memory through pci_memory_*() instead of
> > cpu_physical_memory_*(). This also provides support for translation and
> > access checking in case an IOMMU is emulated.
> >
> > Memory maps are treated as remote IOTLBs (that is, translation caches
> > belonging to the IOMMU-aware device itself). Clients (devices) must
> > provide callbacks for map invalidation in case these maps are
> > persistent beyond the current I/O context, e.g. AIO DMA transfers.
> >
> > Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
> > ---

[snip]

> > +static inline void pci_memory_read(PCIDevice *dev,
> > + pcibus_t addr,
> > + uint8_t *buf,
> > + pcibus_t len)
> > +{
> > + pci_memory_rw(dev, addr, buf, len, 0);
> > +}
> > +
> > +static inline void pci_memory_write(PCIDevice *dev,
> > + pcibus_t addr,
> > + const uint8_t *buf,
> > + pcibus_t len)
> > +{
> > + pci_memory_rw(dev, addr, (uint8_t *) buf, len, 1);
> > +}
> > +
> > #endif
> 
> The functions pci_memory_read and pci_memory_write not only read
> or write byte data but many different data types which leads to
> a lot of type casts in your other patches.
> 
> I'd prefer "void *buf" and "const void *buf" in the argument lists.
> Then all those type casts could be removed.
> 
> Regards
> Stefan Weil

I only followed an approach similar to how cpu_physical_memory_{read,write}()
is defined. I think I should change both cpu_physical_memory_* stuff and
pci_memory_* stuff, not only the latter, if I decide to go on that
approach.


	Eduard