x86: clean up and and print out initial max_pfn_mapped

Do this so we can check the range that is mapped before
init_memory_mapping().

To be able to print out meaningful info, we first have to fix
64-bit to have max_pfn_mapped assigned before that call. This
also unifies the code-path a bit.

[ Impact: print more debug info, cleanup ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49BF0978.40605@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/setup.c

@@ -862,12 +862,16 @@ void __init setup_arch(char **cmdline_p)
 		max_low_pfn = max_pfn;
 
 	high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
+	max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;
 #endif
 
 #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
 	setup_bios_corruption_check();
 #endif
 
+	printk(KERN_DEBUG "initial memory mapped : 0 - %08lx\n",
+			max_pfn_mapped<<PAGE_SHIFT);
+
 	reserve_brk();
 
 	/* max_pfn_mapped is updated here */

arch/x86/mm/init.c

@@ -132,12 +132,11 @@ static void __init find_early_table_space(unsigned long end, int use_pse,
 	 */
 #ifdef CONFIG_X86_32
 	start = 0x7000;
+#else
+	start = 0x8000;
+#endif
 	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
 					tables, PAGE_SIZE);
-#else /* CONFIG_X86_64 */
-	start = 0x8000;
-	e820_table_start = find_e820_area(start, end, tables, PAGE_SIZE);
-#endif
 	if (e820_table_start == -1UL)
 		panic("Cannot find space for the kernel page tables");