Hi, Continuing the discussion, I have some more query. We are planning to design a PCIe based card which will function as an accelerator. Now, there can be more than 1 cards in a node. In some cases, i may want to give same input data to both the cards. I have stored my input data to one dma'ble buffer. Then i am asking both the cards to do READ DMA to that buffer. 1) Can this be achievable & How ? 2) As we discussed, pci_alloc_consistent() may not be helpful. In case of streaming mapping ,If I have allocated one kernel buffer(using kmalloc or get_free_pages) and mapped it for card 1 using pci_map_single, then can I map the same buffer at same time for card 2 without any unmapping ? Thanks, Yogeshwar On Fri, Jan 23, 2009 at 12:32 AM, Grant Grundler <grundler@xxxxxxxxxxxxxxxx> wrote: > On Thu, Jan 22, 2009 at 04:56:22PM +0530, yogeshwar sonawane wrote: >> Hi all, >> >> If there are multiple PCIe cards of the same type, e.g. 3 or 4 network >> controllers, in a node. >> Now, if one allocates a buffer using pci_alloc_consistent() using >> pci_dev struct of one of the card. >> >> 1) Whether that buffer can be used by remaining cards also ? >> OR >> Whether DMA addresses returned by pci_alloc_consistent() can be used >> by all the cards explained in above situation ? > > What bjorn said. > >> 2) What will be the case for multiple platforms/architectures ? > > pci_alloc_consistent() should conform to Documentation/DMA-API.txt > and Documentation/DMA-mapping.txt. This is true for any platform or > architecture. > > BTW, the latter should be moved to Documentation/PCI....Jesse? > > >> 3) There can be multiple PCIe bridges giving multiple slots on some machines. >> What will happen, when above situation is considered in such machines ? > > What Bjorn said. > > hth, > grant > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
