Linux Zero Copy

Question

I have a PCI device that needs to read and write from userspace. I'm trying to use zero copy; is there a way to allocate, pin, and get the physical address of a userspace address completely within userspace or do I need to have a kernel module that, say, calls virt_to_phys or get_user_pages? The device's memory is mapped into userspace memory via MMIO so I can pass it any data that's needed. Thanks.

score 1 · Accepted Answer · answered Mar 03 '12 at 23:40

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It was a total hack, but I limited Linux to a range of memory and used MMIO to allocate memory for my device that the kernel was unaware of.

answered Mar 03 '12 at 23:40

Jonathan

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score 0 · Answer 2 · answered Jun 08 '12 at 12:00

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Basically you need the memory to be DMA-able, and as far as I know only a kernel module can do that. See http://lxr.free-electrons.com/source/Documentation/PCI/PCI-DMA-mapping.txt

answered Jun 08 '12 at 12:00

benzaita

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Linux Zero Copy

2 Answers2