On Wed, May 21, 2003 at 11:16:49AM +0530, Ashish anand wrote: > I saw a good bit of discussion about CONFIG_MIPS_UNCACHED but > still i am yet to know... > > If I want to use CONFIG_MIPS_UNCACHED (ignoring performance) > what all the side-effects and any restrictions that linux should > take care in software ? > > I observed something surprising on my R4k mips system(virtually indexed > caches), after i use this option my driver never got status updation by > device in transmit and receive decriptors in system memory , Irrespective > of I (flushed+invalidate) caches or not... Descriptors sounds like networking. Network descriptors should usually be stored in uncached or otherwise coherent space that is allocated through pci_alloc_consistent anyway. If you do that CONFIG_MIPS_UNCACHED should not make any difference anymore. > if i don't use CONFIG_MIPS_UNCACHED then before checking status I need to > (flush+invalidate) cache and whole thing works great... That's a funny bug. Normally the opposite behaviour would be expected for a bug ... Ralf
