From: David Woodhouse <dw...@infradead.org> Date: Mon, 19 Feb 2018 15:24:18 +0000
>> For one, the sparc specific code allows mmap'ing any address range >> within a PCI bus device. The generic code does not allow that. > > > You mean any address range in a given PCI bus even if there is no > actual device with a BAR at the corresponding address? > > Would I be right to assume this was only available through the legacy > procfs API? I think it should be possible to accommodate it, and it > does look like I'd missed this requirement the first time round; thanks > for pointing it out. It was probably the case that only procfs could do it. It is the mechanism by which we were able to let the X server poke around in VGA ISA space. It does a bus I/O space map for the bus device above the VGA card.