> > In any case, doing PAGE_KERNEL_NOCACHE for DMA memory is incorrect on > > many architectures. So at this stage, there's no much option but ifdef I > > suspect for now until this is fixed properly. > > Ok. But, i am not sure whether Greg will agree to this. If, Ok, is the > following patch i sent earlier Ok ? > > http://lkml.org/lkml/2009/6/5/462, Not really. You probably want to use a constant (call it MY_DMA_MAP_PGPROT), and in a header, you have a bunch of ifdef's that set it to PAGE_KERNEL, PAGE_KERNEL_NOCACHE or PAGE_KERNEL_NC depending on what's needed. Today, you can pretty much assume that - x86*, sparc*, ia64*, alpha, ... needs PAGE_KERNEL - powerpc needs PAGE_KERNEL if !CONFIG_NOT_COHERENT_CACHE - powerpc needs PAGE_KERNEL_NC if CONFIG_NOT_COHERENT_CACHE - ARM and MIPS, I think, needs PAGE_KERNEL_NOCACHE - ... others I don't know. Cheers, Ben. > Regards-- > Subrata > > > > > It does make sense to want to have some memory like that shared between > > user space and DMA, though I don't know what the right approach that > > works on all archs is at this stage. Worth asking the Alsa guys, I think > > they have similar issues :-) > > > > But doing double buffering might do the trick fine for now. > > > > Cheers, > > Ben. > > > > > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
