Messages in this thread | | | Date | Mon, 7 Jun 1999 15:35:34 +1000 | From | Paul Mackerras <> | Subject | Re: RFC: Devices, buses and hotplug |
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David S. Miller <davem@redhat.com> wrote:
> I never got down to facts about whether it was an issue of the PPC > supporting it in HW or the PPC developers just mis-designed their > framework and now require big endian friendly devices just to work.
PPC has byte-swapped load and store instructions, and the in*/out*/read*/write* family of macros use them. It doesn't have the endianness selectable on a per-page basis like the ultra does, where you can do a normal load/store to a little-endian page and the hardware byte-swaps it for you (if I've understood it correctly).
So if you have a frame buffer with multi-byte pixels, you can either use a big-endian aperture if there is one, or have versions of all your framebuffer access routines which use the byte-swapped loads and stores instead of normal loads and stores. That would be possible (and would even be just as fast) but it would be a little ugly.
Paul.
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