If I have only the physical address of device buffer (PCIe), how can I map this buffer to user-space?

Question

If I have only the physical address of the memory buffer to which is mapped the device buffer via the PCI-Express BAR (Base Address Register), how can I map thi

Answer 1

Mapping PCI resource is dependent on the architecture.

BARs are already available to userspace with the sysfs files /sys/bus/pci/devices/*/resource*, which support mmap.

This is implemented by the function pci_mmap_resource in drivers/pci/pci-sysfs.c, which ends up calling pci_mmap_page_range.