On Mon, 2007-01-15 at 10:20 -0800, Arjan van de Ven wrote: > if you need that much you probably should redesign your algorithms to > not need vmalloc in the first place....
I think you've convinced me that vmalloc is not a good choice when a driver needs a large buffer (many megabytes) for DMA. In this case, we need a large ring buffer for reception of isochronous packets from a firewire device. If I understand you correctly, you are suggesting that this buffer be obtained as followed: 1. Application performs malloc() in user-space and mmap()s it. 2. Driver uses vmalloc_to_page() on every page of the malloc'ed memory and constructs a scatter-gather list. 3. Map the sg list with pci_map_sg(). 4. Commence DMA. Is that correct? In particular, does it do the right thing in terms of pinning the memory and dealing with high memory? I notice that the block I/O API has some convenience functions for this, but this is not a block device. Are there some other convenience functions that can be used? Forgive me if these are obvious questions -- I'm not the developer of video1394, but I'd still like get it right for the new firewire stack that's being developed. Thanks, David - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
