On Tue, 2005-05-24 at 21:17 -0500, Kumar Gala wrote: > On May 24, 2005, at 8:30 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... > > > > What are the good and unavoidable uses of it currently that cannot be > > replaced by some sort of ioremap ? > > Do you propose to fixup ioremap to allocate large page resources (BATs > and CAMs) going forward?
Do we really ever need them for anything but RAM mapping ? > > (Note that if the answer to the above is: page tables exist too late, I > > already have a reply: our initialisations happen too early, let's move > > things around so that ioremap is useable... pretty much everything > > needed to setup kernel page tables & have working ioremap can be done > > without any HW device access so ...) > > Do you have any proposed solution for early console access? I'm > guessing that most of the need for early access is for some sort of > console (serial) for early debug output. How do we implement io_block_mapping() on CPUs without a hash table ? We need page tables for these so we can have ioremap working. On CPUs with a hash, we could just shove entries in the hash... though we may need a mecanism to bolt them or convert those mappings to page tables once those are available. > Also does this mean we would drop ppc_md.setup_io_mappings() complete? Does it really make sense ? I always disliked it. Ben.
