Displaying 7 results from an estimated 7 matches for "armism".
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armisd
2018 Aug 08
2
[RFC 0/4] Virtio uses DMA API for all devices
...ly change that contract
> through using a flag that says you pass bus address everything is fine.
For us a "bus address" is behind the iommu so that's what
VIRTIO_F_IOMMU_PLATFORM does already. We don't have the concept of a
bus address that is different. I suppose it's an ARMism to have DMA
offsets that are separate from iommus ?
> Note that in practice your scheme will probably just work for your
> initial prototype, but chances are it will get us in trouble later on.
Not on pseries, at least not in any way I can think of mind you... but
maybe other architectures...
2018 Aug 08
2
[RFC 0/4] Virtio uses DMA API for all devices
...ly change that contract
> through using a flag that says you pass bus address everything is fine.
For us a "bus address" is behind the iommu so that's what
VIRTIO_F_IOMMU_PLATFORM does already. We don't have the concept of a
bus address that is different. I suppose it's an ARMism to have DMA
offsets that are separate from iommus ?
> Note that in practice your scheme will probably just work for your
> initial prototype, but chances are it will get us in trouble later on.
Not on pseries, at least not in any way I can think of mind you... but
maybe other architectures...
2018 Aug 08
0
[RFC 0/4] Virtio uses DMA API for all devices
...gt; > through using a flag that says you pass bus address everything is fine.
>
> For us a "bus address" is behind the iommu so that's what
> VIRTIO_F_IOMMU_PLATFORM does already. We don't have the concept of a
> bus address that is different. I suppose it's an ARMism to have DMA
> offsets that are separate from iommus ?
No, a lot of platforms support a bus address that has an offset from
the physical address. including a lot of power platforms:
arch/powerpc/kernel/pci-common.c: set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
arch/powerpc/platform...
2018 Aug 07
2
[RFC 0/4] Virtio uses DMA API for all devices
On Tue, 2018-08-07 at 06:55 -0700, Christoph Hellwig wrote:
> On Tue, Aug 07, 2018 at 04:42:44PM +1000, Benjamin Herrenschmidt wrote:
> > Note that I can make it so that the same DMA ops (basically standard
> > swiotlb ops without arch hacks) work for both "direct virtio" and
> > "normal PCI" devices.
> >
> > The trick is simply in the arch to
2018 Aug 07
2
[RFC 0/4] Virtio uses DMA API for all devices
On Tue, 2018-08-07 at 06:55 -0700, Christoph Hellwig wrote:
> On Tue, Aug 07, 2018 at 04:42:44PM +1000, Benjamin Herrenschmidt wrote:
> > Note that I can make it so that the same DMA ops (basically standard
> > swiotlb ops without arch hacks) work for both "direct virtio" and
> > "normal PCI" devices.
> >
> > The trick is simply in the arch to
2018 Aug 08
2
[RFC 0/4] Virtio uses DMA API for all devices
...ng a flag that says you pass bus address everything is fine.
> >
> > For us a "bus address" is behind the iommu so that's what
> > VIRTIO_F_IOMMU_PLATFORM does already. We don't have the concept of a
> > bus address that is different. I suppose it's an ARMism to have DMA
> > offsets that are separate from iommus ?
>
> No, a lot of platforms support a bus address that has an offset from
> the physical address. including a lot of power platforms:
Ok, just talking past each other :-) For all the powerpc ones, these
*do* go through the iom...
2018 Aug 08
2
[RFC 0/4] Virtio uses DMA API for all devices
...ng a flag that says you pass bus address everything is fine.
> >
> > For us a "bus address" is behind the iommu so that's what
> > VIRTIO_F_IOMMU_PLATFORM does already. We don't have the concept of a
> > bus address that is different. I suppose it's an ARMism to have DMA
> > offsets that are separate from iommus ?
>
> No, a lot of platforms support a bus address that has an offset from
> the physical address. including a lot of power platforms:
Ok, just talking past each other :-) For all the powerpc ones, these
*do* go through the iom...