UIO Kernel Driver with Buildroot and QEMU

[Kenneth Adam Miller]

So I'm building a uio kernel driver with buildroot, and I've gotten the
driver to compile, installed it and can insmod it in the final buildroot
target after booting the image with QEMU.

I'm on linux kernel version 3.14, and I followed the guide here:

https://www.kernel.org/doc/htmldocs/uio-howto/userspace_driver.html

And it describes the location on where the device file that should be
opened by userland code as either one of two locations:

/dev/uioX, with X being a number

or /sys/class/uio/uioX

But the each of following returns nothing:

ls /dev/uio*
ls /sys/class/uio/

After I compile the uio example that is provided in the linux source at
source/drivers/uio/uio.c and uio_dmem_genirq.c, and insmod them, I do
modprobe uio and modprobe uio_dmem_genirq and each of those return nothing.
However, I do see that /sys/modules/uio and /sys/modules/uio_dmem_genirq


What am I doing wrong? Or where are the respective device files that I'm
supposed to use in my userland driver process?

int fd = open("where is it!!?");
mmap(...., fd,..);
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