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 Tragödie, das andere Mal als Farce