On Wed, 2005-05-25 at 00:45 -0400, Dan Malek wrote: > On May 24, 2005, at 9:30 PM, Benjamin Herrenschmidt wrote: > > > As the subject says ... it's the source of endless headaches, is used > > in > > a way that often prevents moving TASK_SIZE freely, etc etc etc... > > Why are you so obsessed about this? :-) We all know what it does > and the limitations. If someone wants to use it in addition to other > kernel configuration options, their particular start up code will have > to be modified to accept this.
We don't "all" know :) It's very easily misused... > > What are the good and unavoidable uses of it currently that cannot be > > replaced by some sort of ioremap ? > > > > (Note that if the answer to the above is: page tables exist too late, > > That's one reason. The other is to pin BATs or large page table entries > for more efficient access. True. > > .... I > > already have a reply: our initialisations happen too early, let's move > > things around so that ioremap is useable > > In most cases you can't do this. There are boards that have to map > serial ports for kgdb or early console debugging. How do they map ? pinning TLBs ? ioremap can do that... ioremap can be made to work very very early ... > There are also > boards that need access to local hardware registers to set up that > early. You may need to map a rom or some other non-volatile storage > to get some system parameters. Ok, well, it's really just requesting for comment here, I don't say I will kill it, just wondering ... Ben.
