On Tue, 2006-09-26 at 10:48 -0600, Matthew Wilcox wrote: > On Tue, Sep 26, 2006 at 08:46:40PM +0530, Adhiraj wrote: > > I found a strange thing on ia64 platform. When I allocate pages using > > __get_free_pages() with GFP_DMA, sometimes the physical addresses of > > allocated pages fall beyond 4G. > > > > I am working on a device driver where the device does not support > > addresses above 4G and hence I have to implement bounce buffers. The > > You should be using the services described in > Documentation/DMA-mapping.txt rather than allocating your own bounce > buffers. Ok, thanks, I will look into it. But the question is why do I get addresses beyond 4G (virt_to_phys() of returned addresses) even when I use GFP_DMA. Is this a known problem on ia64? > > > The dma mask for the driver is set to 64 bits using pci_set_dma_mask(). > > Well, that's one of your problems right there .... if your device can > only DMA up to 4GB then you should set it to DMA_32BIT_MASK. > > - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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