On Tue, Oct 20, 2015 at 6:54 PM, Greg KH <[email protected]> wrote: > On Tue, Oct 20, 2015 at 11:58:21AM -0400, Kenneth Adam Miller wrote: > > 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 > > uio.ko is the uio "core", you need a uio driver in order to actually use > it. > > uio_dmem_genirq is a uio driver, have you added the needed device tree > entries to have it actually create a device for you? Without them, this > driver can not find any hardware to bind to, and as such, no device node > will ever be created. >
I didn't know about that. How do I do that? I'm using buildroot; I guess there's something missing in menuconfig or linux-menuconfig. > > I would suggest reading the UIO documentation, it should explain all of > this for you already. If not, specific questions are always gladly > answered. > The one that I linked? I read that repeatedly. What other documentation is there to read? I also read from Essential Linux Device Drivers, and none of them explained that. There has to be something I'm missing. Thanks a lot! > > thanks, > > greg k-h >
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