UIO memmap of PCi devices not working?

[Joakim Tjernlund]

On Thu, 2017-09-07 at 17:16 +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2017-09-06 at 15:20 +0000, Joakim Tjernlund wrote:
> > Having problems to mmap PCI UIO devices and stumbeled over this page:
> >  http://billfarrow.blogspot.se/2010/09/userspace-access-to-pci-memory.html
> > it claims some adjustments are needed for UIO mmap over PCI to work.
> > These are #if 0 ATM and trying to enable them fails build.
> > 
> > Can this be fixed to at least build again ?
> > The reason for having #if 0 in the first place appears to be old X servers,
> > is that still true? Can the special casing be removed now?
> 
> This article seems out of date... I *think* things should work without
> change by just mmap'ing the appropriate sysfs files. I'm not sure why
> the author thought that had to be ifdef'ed out...

Isn't that what the article is doing(mmaping sysfs files)?
And the article author is #ifdefing it back, not out.

> 
> Let me know if you have problems.

Sure, we still are looking 

> 
> As far as I know, the generic code will call pci_resource_to_user()
> which on powerpc will return a physical address that already includes
> the offset, which is why we don't later add it.
> 
> Now we could probably tear all that out and use the new generic code
> instead as I *think* X has (very) long been fixed but I'd have to spend
> some time triple checking and testing on old HW which I don't have the
> bandwidth for right now. 

Could you fixup the code which is now #if 0 ? I wan't to test the
difference and I not sure how to fix the build problem after changing
those two #if 0 to #if 1
Even better if they could be a CONFIG option instead.

 Jocke