x86: extend e820 early_res support 32bit -fix #3

introduce init_pg_table_start, so xen PV could specify the value.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index c216d3c..0b6cb9f 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -76,7 +76,8 @@
 		reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
 	}
 #endif
-	reserve_early(__pa_symbol(&_end), init_pg_tables_end, "INIT_PG_TABLE");
+	reserve_early(init_pg_tables_start, init_pg_tables_end,
+			"INIT_PG_TABLE");
 
 	reserve_ebda_region();
 
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index b2cc737..bef4618 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -194,6 +194,7 @@
 	xorl %ebx,%ebx				/* %ebx is kept at zero */
 
 	movl $pa(pg0), %edi
+	movl %edi, pa(init_pg_tables_start)
 	movl $pa(swapper_pg_pmd), %edx
 	movl $PTE_ATTR, %eax
 10:
@@ -228,6 +229,7 @@
 page_pde_offset = (__PAGE_OFFSET >> 20);
 
 	movl $pa(pg0), %edi
+	movl %edi, pa(init_pg_tables_start)
 	movl $pa(swapper_pg_dir), %edx
 	movl $PTE_ATTR, %eax
 10:
diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index 08b47a2..de9c5ee 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -71,6 +71,7 @@
 /* This value is set up by the early boot code to point to the value
    immediately after the boot time page tables.  It contains a *physical*
    address, and must not be in the .bss segment! */
+unsigned long init_pg_tables_start __initdata = ~0UL;
 unsigned long init_pg_tables_end __initdata = ~0UL;
 
 /*
@@ -485,6 +486,10 @@
 		return;
 	}
 
+	printk(KERN_INFO "old RAMDISK: %08llx - %08llx\n", ramdisk_image,
+			ramdisk_end);
+
+
 	if (ramdisk_end <= end_of_lowmem) {
 		/* All in lowmem, easy case */
 		/*
@@ -511,6 +516,8 @@
 			 "NEW RAMDISK");
 	initrd_start = ramdisk_here + PAGE_OFFSET;
 	initrd_end   = initrd_start + ramdisk_size;
+	printk(KERN_INFO "Allocated new RAMDISK: %08llx - %08llx\n",
+			 ramdisk_here, ramdisk_here + ramdisk_size);
 
 	do_relocate_initrd = true;
 }