IOMMU disable in kernel

[emintz]

Hi,

We have P2041RDB with DDC 1553 (Muxbus) PCIe card inside. In order to enable DMA mode of the card, the vendor requests to disable IOMMU support in the Linux kernel. The question is, what the impact of the IOMMU disabling? 

Thanks

[yipingwang]

Hello Eli Mintz ,

PAMU(IOMMU) is used for hypervisor case. Typically, a PAMU resides astride the boundary between the coherency and I/O domains.

The FSL DPAA QBMAN drivers have an explicit dependency (for stashing) on the PAMU driver.

If you disable PAMU, then there would be issues with QBMAN drivers.

Have a great day,
TIC

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