On Wed, 30 Nov 2005, Gerhard Pircher wrote:
I have another question regarding the cputable.c file. Ken Moffat commented
out CPU_FTR_NEED_COHERENT for the AmigaOne platform. I tried to find
information about why this define is needed, but couldn't find anything.
Does anybody know, how this affects the functionality of the kernel on PPC
745x CPUs?
Hi again, Gerhard.
for *that* question I can remember the answer - on the 7455 I was
using, it wouldn't boot with CPU_FTR_NEED_COHERENT (that definition was
added to cputable.c around maybe 2.6.9, just after I got my a1 running
2.6) - it was added to work around errata in the 745x cpus, check the
linuxppc-dev list archives from late 2004. "wouldn't boot" as in "died
*very* early in the boot".
As I read this, potentially you might get dma corruption if the
hardware doesn't support coherent dma : the hardware (or the udev
implementation) didn't [ dunno if that has changed ].
Ken
--
das eine Mal als Trag?die, das andere Mal als Farce
