Patch for sparsemem support

[Chad Reese <creese@caviumnetworks.com>]

The patch below allows sparsemem to work for Mips64. This is my first foray into 
the boot memory handling code, so hopefully I haven't made any serious blunders. 
Unfortunately the Octeon processor I made the changes for isn't currently in the 
linux-mips.org tree. This means there isn't an example of sparsemem usage yet. I 
plan to work at fixing this soon.

Other than various ifdef changes, the most important change was moving 
memory_present() in arch/mips/kernel/setup.c. When you're using sparsemem 
extreme, this function does an allocate for bootmem. This would always fail 
since init_bootmem hasn't been called yet. I moved memory_present after 
free_bootmem. This only marks actual memory ranges as present instead of the 
entire address space.

This patch was made against 2.6.16.16

Chad

Signed-off-by: Chad Reese  <creese@caviumnetworks.com>

  arch/mips/kernel/setup.c     |    3 +--
  arch/mips/mm/init.c          |    2 +-
  include/asm-mips/page.h      |    2 ++
  include/asm-mips/sparsemem.h |   14 ++++++++++++++
  include/linux/mm.h           |    2 +-
  include/linux/mmzone.h       |    1 +
  6 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index d9293c5..406afce 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -358,8 +358,6 @@ static inline void bootmem_init(void)
  	}
  #endif

-	memory_present(0, first_usable_pfn, max_low_pfn);
-
  	/* Initialize the boot-time allocator with low memory only.  */
  	bootmap_size = init_bootmem(first_usable_pfn, max_low_pfn);

@@ -413,6 +411,7 @@ static inline void bootmem_init(void)

  		/* Register lowmem ranges */
  		free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
+		memory_present(0, curr_pfn, curr_pfn + size - 1);
  	}

  	/* Reserve the bootmap memory.  */
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 0ff9a34..f151373 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -228,7 +228,7 @@ void __init mem_init(void)
  	for (tmp = 0; tmp < max_low_pfn; tmp++)
  		if (page_is_ram(tmp)) {
  			ram++;
-			if (PageReserved(mem_map+tmp))
+			if (PageReserved(pfn_to_page(tmp)))
  				reservedpages++;
  		}

diff --git a/include/asm-mips/page.h b/include/asm-mips/page.h
index 399d731..103290a 100644
--- a/include/asm-mips/page.h
+++ b/include/asm-mips/page.h
@@ -145,11 +145,13 @@ typedef struct { unsigned long pgprot; }

  #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)

+#ifndef CONFIG_SPARSEMEM
  #ifndef CONFIG_NEED_MULTIPLE_NODES
  #define pfn_to_page(pfn)	(mem_map + (pfn))
  #define page_to_pfn(page)	((unsigned long)((page) - mem_map))
  #define pfn_valid(pfn)		((pfn) < max_mapnr)
  #endif
+#endif

  #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
  #define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
diff --git a/include/asm-mips/sparsemem.h b/include/asm-mips/sparsemem.h
new file mode 100644
index 0000000..795ac6c
--- /dev/null
+++ b/include/asm-mips/sparsemem.h
@@ -0,0 +1,14 @@
+#ifndef _MIPS_SPARSEMEM_H
+#define _MIPS_SPARSEMEM_H
+#ifdef CONFIG_SPARSEMEM
+
+/*
+ * SECTION_SIZE_BITS		2^N: how big each section will be
+ * MAX_PHYSMEM_BITS		2^N: how much memory we can have in that space
+ */
+#define SECTION_SIZE_BITS       28
+#define MAX_PHYSMEM_BITS        35
+
+#endif /* CONFIG_SPARSEMEM */
+#endif /* _MIPS_SPARSEMEM_H */
+
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 279446e..a1c4788 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -506,7 +506,7 @@ static inline void set_page_links(struct
  	set_page_section(page, pfn_to_section_nr(pfn));
  }

-#ifndef CONFIG_DISCONTIGMEM
+#if !defined(CONFIG_DISCONTIGMEM) && !defined(CONFIG_SPARSEMEM)
  /* The array of struct pages - for discontigmem use pgdat->lmem_map */
  extern struct page *mem_map;
  #endif
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index ebfc238..807616f 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -14,6 +14,7 @@
  #include <linux/init.h>
  #include <linux/seqlock.h>
  #include <asm/atomic.h>
+#include <asm/page.h>

  /* Free memory management - zoned buddy allocator.  */
  #ifndef CONFIG_FORCE_MAX_ZONEORDER