pci_request_region_exclusive - Reserved PCI I/O and memory resource
int pci_request_region_exclusive(struct pci_dev * pdev, int bar, const char * res_name);
Mark the PCI region associated with PCI device pdev BR bar as being reserved by owner res_name. Do not access any address inside the PCI regions unless this call returns successfully.
Returns 0 on success, or EBUSY on error. A warning message is also printed on failure.
The key difference that _exclusive makes it that userspace is explicitly not allowed to map the resource via /dev/mem or sysfs.
|January 2017||Kernel Hackers Manual 4.8.|