On Tue, 12 April 2005 11:07:38 +0100, Chris Elston wrote: > > Thanks for everyone's input on this, I've moved the kernel virtual > base address to 0xa0000000, and it works fine now. > > I'm still not convinced that this is a future proof solution > though. What happens when I get a board with 512MB Flash 1GB SDRAM? > I can push the top of the SDRAM out to the high mem area, but I'll > have to encroach further into user space to map the Flash. There's > no good reason that the whole of the Flash need be mapped at the same > time. (Perhaps performance?)
Definitely performance. At the end of the day, you need a bigger namespace of some sorts. Possible solutions are: o a 64bit machine, o a 4GiB/4GiB kernel/user split and o a PPC440 with 36bit addressing and some hardware and ioremap tricks to move flash above the 32bit limit. The 4/4 split also costs some performance. It doesn't violate the 'flash read must be atomic' requirement, though. J?rn -- ...one more straw can't possibly matter... -- Kirby Bakken
