memory allocation for DMA (how to make bdbuf use non-cacheable region for SD card read and write reuqest)

Sebastian Huber sebastian.huber at
Wed Sep 2 13:56:11 UTC 2015

On 02/09/15 15:33, Chan Kim wrote:
> My question is :  how come the buffer used for SD card read or write request from the bdbuf is allocated in cacheable memory? I guess there should be setting that tells bdbuf to use some area that the bsp assigned for DMA(non-cacheable). Or , maybe I should map the buffer address to non-cacheable adderss and copyit myself?(should be slow). What is the correct method?

It makes no sense to put the buffers in non-cacheable memory. The 
buffers are already cache line aligned, so you can safely use cache 
flush/invalidate operations or use a bounce buffer.

Sebastian Huber, embedded brains GmbH

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