From: Paolo Bonzini <pbonzini@redhat.com>
To: Luigi Rizzo <rizzo@iet.unipi.it>
Cc: Giuseppe Lettieri <giuseppe.lettieri@iet.unipi.it>,
qemu-devel@nongnu.org, v.maffione@gmail.com
Subject: Re: [Qemu-devel] bypassing pci_dma_read() and pci_dma_write() ?
Date: Fri, 18 Jan 2013 17:49:32 +0100 [thread overview]
Message-ID: <50F97D1C.70003@redhat.com> (raw)
In-Reply-To: <20130118163329.GB76938@onelab2.iet.unipi.it>
Il 18/01/2013 17:33, Luigi Rizzo ha scritto:
>> > First, host memory mappings could change (though they rarely do on PC).
>> > The result of address_space_map is not guaranteed to be stable. To
>> > avoid problems with this, however, you could use something like
>> > hw/dataplane/hostmem.c and even avoid address_space_map altogether.
> I'll look into that. Hopefully there is something that i can
> use as a notification that the mapping has changed...
Yes, that's the MemoryListener interface that hw/dataplane/hostmem.c uses.
>> > Second, that pci_dma_*() could have the addresses translated by an
>> > IOMMU. virtio is documented to have "real" physical memory addresses,
>> > but this does not apply to other devices.
> I see. I suppose the ability to have an iommu depends on the
> specific NIC ? I am only planning to use the above shortcut for
> e1000.
It depends on the bus, in this case PCI.
Paolo
next prev parent reply other threads:[~2013-01-18 16:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-18 16:04 [Qemu-devel] bypassing pci_dma_read() and pci_dma_write() ? Luigi Rizzo
2013-01-18 16:14 ` Paolo Bonzini
2013-01-18 16:33 ` Luigi Rizzo
2013-01-18 16:49 ` Paolo Bonzini [this message]
2013-01-19 0:58 ` Luigi Rizzo
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