On Wed, 2008-08-06 at 20:49 -0500, Kumar Gala wrote: > On Aug 6, 2008, at 5:28 PM, Benjamin Herrenschmidt wrote: > > > > >> there is a bunch of error checking and difference in semantics that > >> you need to fix. I think introduce a new API for this is silly, > >> especially since we expect there to only be one actual invocation of > >> the API for serial console access. > > > > Not necessarily.... > > > > There's another aspect to BAT mappings here. First, they should be > > permanent (ie, not unmappable). That way, we have ioremap just use > > an existing BAT mapping when asked for a device that is covered > > by a BAT. This allows to have platform code do something like setup > > a BAT over a bunch of SOC registers or over a device, to automagically > > get drivers doing ioremap to that area benefit from it. > > why should they be permanent.. We could implement reference counting > around the regions and free BATs if the count = 0.
Do we care ? > I'm more concerned about this being implemented around the existing > ioremap core in __ioremap(). We can easily use a flag bit to say use > "large mappings" or the fact that mem_init_done == 0. mem_init_done isn't a good indication. We can do page tables when it's 0, we would have to use a separate mem_preinit_done or something :-) I initially also though about a flag to ioremap_prot to be honest. But it does obfuscate the normal ioremap code path and if there's a flag, that means that callers know the difference and thus may as well call a separate function, don't you think ? Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
