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I want to reserve a large amount (~1 gigabyte) of contiguous memory for DMA from a device. The entire purpose of this particular Linux box is to run a single application which uses the device. The device does large transfers of ~10-200MB per operation.

To be clear, put up this question for the next guy. Expect to have an answer somewhat shortly.

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I don't think you'll be able to. Instead, you'll have to "fake it" as described here.

The last time I checked (it's been a while), the CMA hadn't been ported to x86 from ARM yet. Even then, that big a buffer is unlikely to work out for you.

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  • Yes, I think the answer is in the direction of adding "memmap=1G$4G" as a kernel boot parameter. Still walking through how to use that reserved 1GB of memory. – Preston L. Bannister Jul 27 at 23:25
  • Yes, that horrible answer was also to get large FPGA DMA pools. – Aaron D. Marasco Jul 28 at 13:51

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