Hi, This patch removes the limitation of 2MB consistent DMA memory on ppc440. Originally consistent_pte was allocated only one page no matter what value of CONFIG_CONSISTENT_SIZE is set. By default CONFIG_CONSISTENT_SIZE is 0x200000. This causes some troubles on high performance I/O applications which may require more than 2MB consistent DMA memory.
The modifications allocate multiple pages for consistent pte table according to CONFIG_CONSISTENT_SIZE. For example if CONFIG_CONSISTENT_SIZE is set to 4MB, 2 pages are allocated for consistent pte table. Please note that CONFIG_CONSISTENT_SIZE cannot be any value. You have to find a free continuous memory space on your system memory mapping. The patch was tested successfully on Ocotea board. But I'm not sure if it works on other systems. Use it at your own risk. However feedback is more than welcome. :) Regards, -Shawn. -------------- next part -------------- A non-text attachment was scrubbed... Name: dma-mapping.patch Type: application/octet-stream Size: 4202 bytes Desc: not available Url : http://ozlabs.org/pipermail/linuxppc-embedded/attachments/20050601/e1c3e086/attachment.obj
