From: Dave H. <dhy...@gm...> - 2008-08-25 07:32:18
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Hi Jason, > I've only worked with buildroot as well. I tried changing > CONSISTENT_DMA_SIZE to SZ_8M in memory.h and then rebuilt the kernel. I > loaded the new kernel on the gumstix and tried calling > dma_alloc_writecombine (passing in a size of 6MB) within a kernel driver, > but it did not work properly (the function returned 0). Do you know why > this didn't work? Am I missing something? Since the DMA allocator is a power of 2 allocator, your allocation request for 6 Mb will actually request 8 Mb (the next higest power of 2). If there is only 8 Mb allocated, and any other allocations (even if only for a few bytes), then your allocation would fail. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |