On Fri, 1 Jun 2012 10:51:38 +0300, Ohad Ben-Cohen <ohad@xxxxxxxxxx> wrote:
> On Fri, Jun 1, 2012 at 10:31 AM, Sjur BRENDELAND
> <sjur.brandeland@xxxxxxxxxxxxxx> wrote:
> > if (virtio_has_feature(vdev, VIRTIO_CONSOLE_USE_DMA_MEM)) {
> > dma_addr_t dma;
> > buf = dma_alloc_coherent(dev, size, &dma, GFP_KERNEL);
> > } else
> > buf = kmalloc(count, GFP_KERNEL);
>
> Something along those lines is also needed for remote processors which
> access memory via an IOMMU (e.g. OMAP4's M3 and DSP).
>
> Allocating the memory via the DMA API will seamlessly configure the
> relevant IOMMU as needed, and will make the buffers accessible to the
> remote processors.
>
> Thanks,
> Ohad.
It seems quite sensible. The formal definition in the spec would be
good. In particular, defining DMA_MEM in a generic (non-Linux) way will
be interesting.
Thanks,
Rusty.
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