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

introduce init_pg_table_start, so xen PV could specify the value.
Signed-off-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/head32.c

@@ -76,7 +76,8 @@ void __init i386_start_kernel(void)
 		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();
 

arch/x86/kernel/head_32.S

@@ -194,6 +194,7 @@ default_entry:
 	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 @@ default_entry:
 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:

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 @@ static void __init reserve_initrd(void)
 		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 @@ static void __init reserve_initrd(void)
 			 "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;
 }

arch/x86/lguest/boot.c

@@ -1011,6 +1011,7 @@ __init void lguest_init(void)
 	 * clobbered.  The Launcher places our initial pagetables somewhere at
 	 * the top of our physical memory, so we don't need extra space: set
 	 * init_pg_tables_end to the end of the kernel. */
+	init_pg_tables_start = __pa(pg0);
 	init_pg_tables_end = __pa(pg0);
 
 	/* Load the %fs segment register (the per-cpu segment register) with
@@ -1064,9 +1065,9 @@ __init void lguest_init(void)
 	pm_power_off = lguest_power_off;
 	machine_ops.restart = lguest_restart;
 
-	/* Now we're set up, call start_kernel() in init/main.c and we proceed
+	/* Now we're set up, call i386_start_kernel() in head32.c and we proceed
 	 * to boot as normal.  It never returns. */
-	start_kernel();
+	i386_start_kernel();
 }
 /*
  * This marks the end of stage II of our journey, The Guest.

arch/x86/xen/enlighten.c

@@ -1211,6 +1211,7 @@ asmlinkage void __init xen_start_kernel(void)
 
 	pgd = (pgd_t *)xen_start_info->pt_base;
 
+	init_pg_tables_start = __pa(pgd);
 	init_pg_tables_end = __pa(pgd) + xen_start_info->nr_pt_frames*PAGE_SIZE;
 
 	init_mm.pgd = pgd; /* use the Xen pagetables to start */
@@ -1246,5 +1247,5 @@ asmlinkage void __init xen_start_kernel(void)
 		add_preferred_console("hvc", 0, NULL);
 
 	/* Start the world */
-	start_kernel();
+	i386_start_kernel();
 }

include/asm-x86/setup.h

@@ -59,9 +59,11 @@ int __init copy_e820_map(struct e820entry *biosmap, int nr_map);
 void __init add_memory_region(unsigned long long start,
 			      unsigned long long size, int type);
 
-extern unsigned long init_pg_tables_end;
 
+void __init i386_start_kernel(void);
 
+extern unsigned long init_pg_tables_start;
+extern unsigned long init_pg_tables_end;
 
 #endif /* __i386__ */
 #endif /* _SETUP */