[openib-general] Re: mstflint failing on sparc64

[Grant Grundler]

On Thu, Jan 06, 2005 at 03:26:13PM -0800, Roland Dreier wrote:
> > > Generally, do yo happend to know if mmapping /dev/mem
> > > to userspace works on this architecture?
> 
> > I can't imagine that it would not.  I will see if I can dig info up.
> > The one thing that is weird on sparc64 is that the pci bus is virtually
> > (not physically) addressed.  I don't know if you take that into account.
> 
> Actually I would suspect that it doesn't.  If you look at drivers/char/mem.c,
> you can see that there's nothing there to set up the IOMMU, so I don't
> think access to PCI space will work -- a simple remap_pfn_range won't work
> (sparc64 doesn't even define pgprot_noncached).

IOMMU is only relevant for DMA.  I read Tom's reply to mean the host
access PCI bus involves a tranlation as well. e.g a 32-bit bus address
is mapped above 4GB in the host physical address space.
ergo reading the BAR values won't give one the physical address one
needs to access and program device registers.

grant