On Fri, 2011-04-22 at 13:19 -0500, James Bottomley wrote: > I looked at converting parisc to sparsemem and there's one problem that > none of these cover. How do you set up bootmem? If I look at the > examples, they all seem to have enough memory in the first range to > allocate from, so there's no problem. On parisc, with discontigmem, we > set up all of our ranges as bootmem (we can do this because we > effectively have one node per range). Obviously, since sparsemem has a > single bitmap for all of the bootmem, we can no longer allocate all of > our memory to it (well, without exploding because some of our gaps are > gigabytes big). How does everyone cope with this (do you search for > your largest range and use that as bootmem or something)? Sparsemem is purely post-bootmem. It doesn't deal with sparse bootmem. :( That said, I'm not sure you're in trouble. One bit of bitmap covers 4k (with 4k pages of course) of memory, one byte covers 32k, and A 32MB bitmap can cover 1TB of address space. It explodes, but I think it's manageable. It hasn't been a problem enough up to this point to go fix it. -- Dave -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
