Messages in this thread | | | Date | 17 Dec 2007 13:41:37 +0100 | Date | Mon, 17 Dec 2007 13:41:37 +0100 | From | Andi Kleen <> | Subject | Re: [RFC PATCH 08/12] PAT 64b: coherent mmap and sysfs bin ioctl |
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On Mon, Dec 17, 2007 at 08:57:50AM +1100, Paul Mackerras wrote: > Greg KH writes: > > > Ok, sorry, it wasn't blindingly obvious that this was for pci sysfs > > devices that are mmaped, that makes a bit more sense. > > > > But I'd like to see what ioctl is wanted here first. > > I believe the ioctl would be to set whether the mapping goes to I/O or > memory space,
x86 cannot really access IO space through mmap so no that wasn't planned
The main planned use was to get the translated bus address (after IOMMU) for a mapping and to set the caching modes.
> So the alternative to the ioctl would be to have multiple files in > sysfs, one per combination of modes -- i.e., 4 files, or 3 if we > exclude the "I/O with write combining" mode, which would be > reasonable.
At least for the IOMMU translation case that wouldn't work.
-Andi
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