Problem mapping small PCI memory space.

["Gianluca Varenni" <gianluca.varenni@gmail.com>]

Hi all.

I'm writing a driver for a PCI board that exposes two memory spaces (out of
the 6 IO address regions).

One of them is 1MB, and I can map it to user level without problems. The
other one is only 512 bytes.
If I try to open it with /dev/mem, it returns EINVAL (the 1MB memory space
is opened without any problem). If I try to expose it through mmap, mmap
succeeds, but I only see garbage at user level. At kernel level, I can
access that 512 bytes memory by using ioremap() on the physical address
returned by pci_resource_start().

Are there any lower limits on the size of a PCI memory region?

Have a nice day
GV