On Thu, 2017-09-07 at 18:33 +1000, Benjamin Herrenschmidt wrote: > On Thu, 2017-09-07 at 07:22 +0000, Joakim Tjernlund wrote: > > 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 This article seems out of date...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. > > Yes sorry that's what I meant. It should work as-is. > > > > > > > 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. > > Hrm it's tricky, you shouldn't just turn that ifdef back on without > also changing pci_resource_to_user().
There are two ifdef to change: __pci_mmap_make_offset(): #if 0 /* See comment in pci_resource_to_user() for why this is disabled */ *offset += hose->pci_mem_offset; #endif and pci_resource_to_user() /* We pass a fully fixed up address to userland for MMIO instead of * a BAR value because X is lame and expects to be able to use that * to pass to /dev/mem ! * * That means that we'll have potentially 64 bits values where some * userland apps only expect 32 (like X itself since it thinks only * Sparc has 64 bits MMIO) but if we don't do that, we break it on * 32 bits CHRPs :-( * * Hopefully, the sysfs insterface is immune to that gunk. Once X * has been fixed (and the fix spread enough), we can re-enable the * 2 lines below and pass down a BAR value to userland. In that case * we'll also have to re-enable the matching code in * __pci_mmap_make_offset(). * * BenH. */ #if 0 else if (rsrc->flags & IORESOURCE_MEM) offset = hose->pci_mem_offset; #endif Problem is that pci_mem_offset is gone, the closed I can find is mem_offset but that is an array,maybe just mem_offset[0] ? > I'm not sure exactly what's going > on in your case, if you have a problem can you add printk to instrument > ? Seems to be something else going on in out board. Anyhow, the mem_offset should be fixed to compile, nice to have it behind a CONFIG option. Then one can start the process to remove the special casing easier. Jocke