paubert at iram.es
Fri Feb 19 01:00:17 EST 1999
On 18 Feb 1999, Jesper Skov wrote:
> >>>>> "Gabriel" == Gabriel Paubert <paubert at iram.es> writes:
> Gabriel> I had the impression that the APUS I/O accesses had to use
> Gabriel> non byte swapped instruction, so that merging the APUS with
> Gabriel> the other would be hard. Is there something I missed ?
> True, APUS doesn't require byte swapping. But I don't see how this
> makes it hard to integrate APUS.
It means that you can't run the same kernel image, it would require
deciding between a byte swapping and non-byte swapping instruction on each
and every in[wl] and out[wl] instruction. It is possible to build a
CHRP/PreP/Pmac kernel and then only select the right drivers, but I can't
see how you can merge CONFIG_APUS in it without a huge performance and/or
size penalty (and do it in an acceptably clean way, I have some ideas
about dirty trick solutions).
> Gabriel> I don't want the kernel to execute conditional code or to
> Gabriel> call a subroutine for every I/O access, this is bloat and/or
> Gabriel> inefficiency for the sake of it.
> This is a valid concern. I don't know if it's possible to do anything
> about this.
> It may be the case that none of the Amiga drivers use the same IO
> macros as other drivers use. As I remember it, there are two set of
> macros. But it's a long time since I looked at that, I could be wrong.
No they don't, have a look at include/asm-ppc/io.h, there is a lot of
ifdef on CONFIG_APUS. This can't reasonably be made into a run time
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