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--- resources:tools-software:linux-software:libiio_tips_tricks [20 Aug 2021 10:15] – [IIO buffer DMA max block size] Michael Hennerich
+++ resources:tools-software:linux-software:libiio_tips_tricks [20 Aug 2021 10:49] (current) – [Capturing large contiguous buffers] Michael Hennerich
@@ Line 58: / Line 58: @@
 <note tip>Depending on your **IIO buffer DMA max block size** and **number of kernel buffer count** you may need to **CMA size**</note>
+===== Capturing large contiguous buffers =====
+  - Set kernel buffer count to 1
+  - Increase **IIO buffer DMA max block size** parameter to at least the size of your desired contiguous buffer
+  - Make sure your CMA size is significantly bigger (CMA is used by various other DMA capable devices in your Linux system)
+  - AXI_DMAC controller limits length of the transfers to 2**DMA_LENGTH_WIDTH. The default is 24 so your max transfer size is 16777216 bytes. You may need to increase that and rebuild your design. Please see here: [[:/resources/fpga/docs/axi_dmac#synthesis_configuration_parameters| Synthesis Configuration Parameters]]

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