pci_alloc_consistent doubt

[Dhananjay Maske]

On Thu, Mar 28, 2013 at 1:14 AM, Dhananjay Maske <
dhananjay.maske87 at gmail.com> wrote:

> Hi All,
>      I am fairly New to Linux kernel Programming and i have few questions
> with respect to pci_alloc_consistent .
>
> 1) as we know pci_alloc_consistent allocates dma buffers which is visible
> to DMA controller as well as CPU.
>     virt_add = pci_alloc_consistent(pdev, size, dma_addr_t bus_adrr);
>
> here it will allocate a buffer and return its virtual address and
> corresponding bus address.
>
> My question is do these two address ultimately point to similar location
> but from different perspectives ?.
>
> 2) After allocating these address, how do we proceed given that i have a
> ASIC register which has the dma_rx_desc_start address ?
>
> 3) Also does all the HW's which support dma have the descriptor data
> structures by provided by Vender or is there any specific format that dev
> has to be aware of for designing such descriptor for that particular driver
> ?
>
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