Noncoherent DMA mappings

Posted May 7, 2021 21:41 UTC (Fri) by alex31 (guest, #67059)
In reply to: Noncoherent DMA mappings by mss
Parent article: Noncoherent DMA mappings

In the microcontroler word, it's possible with some high end MCU to achieve non contiguous dma transactions without IOMMU. There is a so called MDMA (master DMA) peripheral which is able to process a linked list of memory to memory transactions. MDMA is also connected to standard DMA, so it can chain several memory to peripheral transactions without the need of triggering ISR between each transaction.

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Noncoherent DMA mappings

Posted May 16, 2021 0:11 UTC (Sun) by bored (guest, #125572) [Link]

A fair number of standard PCI/etc devices are capable of scatter gather operations as well. That tends to be the default for some classes of (storage for example) adapters. Managing those page lists though traditionally could become a bit unwieldy, that is part of what this patch set aims to solve (AFAIK). Of course keeping the buffers continuous has a number of perf advantages as well which again has been part of the recent work.