From: Andy Whitcroft Date: Thu, 23 Jun 2005 07:08:00 +0000 (-0700) Subject: [PATCH] sparsemem hotplug base X-Git-Tag: v2.6.13-rc1~68^2~512 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=29751f6991e845f7d002a6ae520bf996b38c8dcd;p=pandora-kernel.git [PATCH] sparsemem hotplug base Make sparse's initalization be accessible at runtime. This allows sparse mappings to be created after boot in a hotplug situation. This patch is separated from the previous one just to give an indication how much of the sparse infrastructure is *just* for hotplug memory. The section_mem_map doesn't really store a pointer. It stores something that is convenient to do some math against to get a pointer. It isn't valid to just do *section_mem_map, so I don't think it should be stored as a pointer. There are a couple of things I'd like to store about a section. First of all, the fact that it is !NULL does not mean that it is present. There could be such a combination where section_mem_map *is* NULL, but the math gets you properly to a real mem_map. So, I don't think that check is safe. Since we're storing 32-bit-aligned structures, we have a few bits in the bottom of the pointer to play with. Use one bit to encode whether there's really a mem_map there, and the other one to tell whether there's a valid section there. We need to distinguish between the two because sometimes there's a gap between when a section is discovered to be present and when we can get the mem_map for it. Signed-off-by: Dave Hansen Signed-off-by: Andy Whitcroft Signed-off-by: Jack Steiner Signed-off-by: Bob Picco Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed