Hello Rolf Eike, On Fri, May 14, 2010 at 10:34 AM, Rolf Eike Beer <eike-kernel@xxxxxxxxx> wrote: > Leon Woestenberg wrote: >> Hello, >> >> my PCIe device supports 64-bit DMA for data, but only 32-bit addresses >> for fetching descriptors from host memory. >> >> How can I allocate consistent memory in the 32-bit address range, even >> though I earlier performed pci_set_dma_mask(..., DMA_64BIT_MASK)? > > Create a pci_pool (see pci_pool_*() in include/linux/pci.h) for the > descriptors. Create the pool with a restriction to 32 bit. > Thanks. Creating a pool with a restriction seems impossible: struct pci_pool *pci_pool_create(const char *name, struct pci_device *dev, size_t size, size_t align, size_t alloc); However, subsequent allocation does allow restrictions: void *pci_pool_alloc(struct pci_pool *pool, gfp_t gfp_flags, dma_addr_t *dma_handle); I had missed that in reading DMA-API.txt What is the actual restriction flag for limiting to 32-bit? I can image this is hard to achieve, say, in a 36-bit physical system (Intel PAE, PowerPC e500, ...) Regards, -- Leon -- 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
