On Thu, Aug 14, 2008 at 10:24 AM, Kumar Gala <[EMAIL PROTECTED]> wrote: >>> what happens if we run out of bats? >> >> Then it returns NULL and the caller must handle it. The board port >> maintainer needs understand the board/CPU/SoC and not depend on more >> BATs than are available. They also need to understand that there is a >> tradeoff between BATs for IO and BATs for RAM. If the board port uses >> up all the BATs for IO, then RAM above 256MB ends up getting mapped >> with PTEs and there is a performance hit. My expectation is that only >> platform code will use this facility. Device drivers should continue >> to use ioremap() and will gain the benefit of the BATs if platform >> code already set them up. I can add some text to the documentation to >> describe this. >> >> I'm not going to make any attempt to fallback to PTEs for IO when >> there isn't enough BATs. Doing so adds an order of magnitude more >> complexity. > > that's fine.. I just didn't look at setbat() to see it errors out. > > Also can we get rid of LOAD_BAT in head_32.S?
Mostly. It is still needed for BAT0 when setting up RAM, but the rest of it can be dumped. g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
