x86, mm: limit MAXMEM on 64-bit

on 64-bit x86 the physical memory limit is controlled by the sparsemem bits - which are 44 bits right now. But MAXMEM (the max pfn number e820 parsing will allow to enter our sizing routines) is set to 0x00003fffffffffff, i.e. 46 bits - that's too large because it overlaps into the vmalloc range. So couple MAXMEM to MAX_PHYSMEM_BITS, and add a comment that the maximum of MAX_PHYSMEM_BITS is 45 bits. Signed-off-by: Ingo Molnar <mingo@elte.hu>
git-mirror · Dec 16, 2008 · b6fd6f2 · b6fd6f2
1 parent cfc3198
commit b6fd6f2
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diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
@@ -146,7 +146,7 @@ static inline void native_pgd_clear(pgd_t *pgd)
 #define PGDIR_MASK	(~(PGDIR_SIZE - 1))
 
 
-#define MAXMEM		 _AC(0x00003fffffffffff, UL)
+#define MAXMEM		 _AC(__AC(1, UL) << MAX_PHYSMEM_BITS, UL)
 #define VMALLOC_START    _AC(0xffffc20000000000, UL)
 #define VMALLOC_END      _AC(0xffffe1ffffffffff, UL)
 #define VMEMMAP_START	 _AC(0xffffe20000000000, UL)

diff --git a/arch/x86/include/asm/sparsemem.h b/arch/x86/include/asm/sparsemem.h
@@ -27,7 +27,7 @@
 #else /* CONFIG_X86_32 */
 # define SECTION_SIZE_BITS	27 /* matt - 128 is convenient right now */
 # define MAX_PHYSADDR_BITS	44
-# define MAX_PHYSMEM_BITS	44
+# define MAX_PHYSMEM_BITS	44 /* Can be max 45 bits */
 #endif
 
 #endif /* CONFIG_SPARSEMEM */