Messages in this thread | | | Date | Sat, 20 Mar 2004 19:22:13 -0500 (EST) | From | Zwane Mwaikambo <> | Subject | Re: can device drivers return non-ram via vm_ops->nopage? |
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On Sat, 20 Mar 2004, Russell King wrote:
> The issues are: > > 1. ALSA wants to mmap the buffer used to transfer data to/from the > card into user space. This buffer may be direct-mapped RAM, > memory allocated via dma_alloc_coherent(), an on-device buffer, > or anything else. > > The user space mapping must likewise be DMA-coherent. > > Currently, ALSA just does virt_to_page() on whatever address it > feels like in its nopage() function, which is obviously not > acceptable for two out of the three specific cases above. > > 2. ALSA wants to _coherently_ share data between the kernel-side > drivers, and user space ALSA library, mainly the DMA buffer > head/tail pointers so both kernel space and user space knows > when the buffer is full/empty.
Doesn't DRI also suffer from the same issues? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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