Description

This kernel module is a PCI device driver. Its purpose is to control the DMA / bus mastering. A program can enable the DMA of a PCI device given its location. The kernel module makes sure that DMA will be disabled when the program terminates.

Usage

In order to use this kernel module, you have first to compile it and load it:

make
sudo insmod pcidma.ko

Let's assume that you have a PCI device on your system, such as:

$ lspci -D | grep Ethernet
0000:42:00.1 Ethernet controller: Intel Corporation Ethernet 10G 2P X520 Adapter (rev 01)

An example program that uses the kernel module to enable DMA is the following:

#include "pcidma.h"

int main(int argc, char **argv)
{
    int fd;
    struct args_enable args;

    args.pci_loc.domain = 0;
    args.pci_loc.bus = 0x42;
    args.pci_loc.slot = 0;
    args.pci_loc.func = 1;

    fd = open("/dev/pcidma", O_RDONLY);
    ioctl(fd, PCIDMA_ENABLE, &args);
    /* do_work(); */
    return 0;
}

Note: In order for the ioctl to succeed, the specified device must not be assigned to another device driver.