From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: Q: uio_generic_pci
Date: Tue, 6 Feb 2018 12:56:14 -0800
Message-ID: <20180206125614.6d6cd31d@xeon-e3>
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To: Ran Shalit <ranshalit@gmail.com>
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On Tue, 6 Feb 2018 12:57:15 +0200
Ran Shalit <ranshalit@gmail.com> wrote:

> Hello,
> 
> I would please like to ask about uio_generic_pci :
> 
> 1. how to set irq from userspace.

No. that is not generally possible.
It is expected that the IRQ will come from the hardware device.
On some hardware it is possible to poke a register and cause an interrupt.

> Is there anything similar to
> echo "3" > /sys/bus/pci/drivers/uio_pci_generic/irq
> in all documentation which talk about it, it is not mentioned (or I
> don't find it):
> https://github.com/rumpkernel/wiki/wiki/Howto:-Accessing-PCI-devices-from-userspace
> http://www.hep.by/gnu/kernel/uio-howto/uio_pci_generic.html
> 
> 2. Is there a way to use dma from userspace with this driver ?

This driver does not provide mappings of the PCI memory regions
so DMA is not possible. Use VFIO-pci or igb_uio instead.