Details
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Type:
Bug
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Status: New
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Priority:
Minor
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Resolution: Unresolved
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Affects Version/s: V3.0.0
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Fix Version/s: None
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Component/s: None
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Labels:None
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Account:SDO Driver (SDODRIVER)
Description
Newer machines/kernels are making excessive use of IOMMUs which cause trouble when trying to map DMA buffers from uio to userspace.
Mapping coherent DMA buffers is also being discouraged (See https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/uio/uio.c?h=v6.10.11&id=576882ef5e7fce030b65c92b508a0f84ea5a81c2)
+ dev_warn(mem->dma_device,
+ "use of UIO_MEM_DMA_COHERENT is highly discouraged");
+
Possible workarounds (may not work, but have shown to work on some platforms):
- Add "iommu.passthrough=1" to kernel command line