From: Scott Wood <[EMAIL PROTECTED]> Date: Tue, 20 May 2008 17:35:56 -0500
> Alan Cox wrote: > >> It looks like we rely on -fno-strict-aliasing to prevent reordering > >> ordinary memory accesses (such as to DMA descriptors) past the I/O > > > > DMA descriptors in main memory are dependant on cache behaviour anyway > > and the dma_* operators should be the ones enforcing the needed behaviour. > > What about memory obtained from dma_alloc_coherent()? We still need a > sync and a compiler barrier. The current I/O accessors have the former, > but not the latter. The __volatile__ in the asm construct disallows movement of the inline asm relative to statements surrounding it. The only reason barrier() in kernel.h needs a memory clobber is because of a bug in ancient versions of gcc. In fact, I think that memory clobber might even be removable. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
