Problem with framebuffer mmap on platforms with large addressing

Benjamin Herrenschmidt benh at
Thu Mar 22 07:49:18 EST 2012

On Wed, 2012-03-21 at 19:45 +0000, Florian Tobias Schandinat wrote:
> I finally found where we started to discuss this issue, for reference
> "sm501fb.c: support mmap on PPC440SPe/PPC440EPx" back in May 2010.
> The thing I don't remember is why we consider exporting the physical
> address to userspace desirable (or even necessary). Fixing the generic
> mmap would be trivial without breaking or adding any userspace ABI, I
> think. Just adding those things to fb_info and adjusting fb_mmap
> should
> do the trick, shouldn't it?

For historical reasons, things like X or directfb used it. Modern X
drivers shouldn't any more, but heh...


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