Hrm... well, that's not the answer that I wanted, but it does explain a lot :-/
It sounds like you know a lot more about what's going on here, Paul, but since it sounds like we're in the same boat, I'm more than willing to help in whatever way I can (especially since I have nothing better to do until I get the ethernet controller working, and that just isn't happening without this fixed :) And thanks for the heads up that setting PAGE_NO_CACHE doesn't work- I'd just tried disabling caches entirely and was about to go in and start mucking with lower level things- starting with a BAT entry :) Back to the debugger... --Gus On Thu, 28 Jun 2001, Paul White wrote: > > Justin, > > >From my recent experience, this does not work. We have a device on our > PCI bus which is DMAing to SDRAM, and so far I can't get anything to > work without cache coherency support in the system controller. > > If you find anything out, please let me know. I may end up adding a new > memory queue for non-cacheable memory, and just use another BAT entry > for some pre-defined amount of memory for a non-cacheable pool. A new > flag to kmalloc() could then be used to get non-cacheable memory. Does > anyone know if anything like this already exists, or if theres a much > easier way around this?? I should hopefully get cache coherency > working, but we have been unable to so far. If I end up doing the work, > I"ll post the patches here. > > Btw.. I attempted to disable cache, as well as simply set the RAM bat's > to PAGE_NO_CACHE, however this does not work because the PowerPC will > throw alignment exceptions whenever a cache instruction is called on > either a non-cached memory region, or if caching is disabled. Just > wanted to give you a heads up on this. > > Paul W. > > > At 04:52 AM 6/28/2001 -0400, Justin (Gus) Hurwitz wrote: > > > >Did yo ever get a reply to this? That sounds like just what I want to do > >(well, it sounds just like what our vxworks code does to do what I want to > >do, which I guess is good enough). > > > >TIA, > >--Gus ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
