linux/i386: re-add and use pre_setup_arch_hook()

Index: head-2008-03-11/arch/i386/kernel/setup-xen.c
===================================================================
@@ -1400,10 +1400,6 @@ void __init setup_bootmem_allocator(void
 			crashk_res.end - crashk_res.start + 1);
 #endif
 #endif
-
-	if (!xen_feature(XENFEAT_auto_translated_physmap))
-		phys_to_machine_mapping =
-			(unsigned long *)xen_start_info->mfn_list;
 }
 
 /*

@@ -1601,6 +1601,7 @@ void __init setup_arch(char **cmdline_p)
 				     VMASST_TYPE_writable_pagetables));
 
 	memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
+	pre_setup_arch_hook();
 	early_cpu_init();
 #ifdef CONFIG_SMP
 	prefill_possible_map();

@@ -1654,8 +1655,6 @@ void __init setup_arch(char **cmdline_p)
 	rd_doload = ((RAMDISK_FLAGS & RAMDISK_LOAD_FLAG) != 0);
 #endif
 
-	setup_xen_features();
-
 	ARCH_SETUP
 	if (efi_enabled)
 		efi_init();

Index: head-2008-03-11/arch/i386/mach-xen/setup.c
===================================================================
@@ -88,17 +88,39 @@ extern void hypervisor_callback(void);
 extern void failsafe_callback(void);
 extern void nmi(void);
 
-unsigned long *machine_to_phys_mapping;
+unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
 EXPORT_SYMBOL(machine_to_phys_mapping);
 unsigned int machine_to_phys_order;
 EXPORT_SYMBOL(machine_to_phys_order);
 
-void __init machine_specific_arch_setup(void)
+void __init pre_setup_arch_hook(void)
 {
-	int ret;
 	struct xen_machphys_mapping mapping;
 	unsigned long machine_to_phys_nr_ents;
 	struct xen_platform_parameters pp;
+
+	init_mm.pgd = swapper_pg_dir = (pgd_t *)xen_start_info->pt_base;
+
+	setup_xen_features();
+
+	if (HYPERVISOR_xen_version(XENVER_platform_parameters, &pp) == 0)
+		set_fixaddr_top(pp.virt_start);
+
+	if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) {
+		machine_to_phys_mapping = (unsigned long *)mapping.v_start;
+		machine_to_phys_nr_ents = mapping.max_mfn + 1;
+	} else
+		machine_to_phys_nr_ents = MACH2PHYS_NR_ENTRIES;
+	machine_to_phys_order = fls(machine_to_phys_nr_ents - 1);
+
+	if (!xen_feature(XENFEAT_auto_translated_physmap))
+		phys_to_machine_mapping =
+			(unsigned long *)xen_start_info->mfn_list;
+}
+
+void __init machine_specific_arch_setup(void)
+{
+	int ret;
 	static struct callback_register __initdata event = {
 		.type = CALLBACKTYPE_event,
 		.address = { __KERNEL_CS, (unsigned long)hypervisor_callback },

@@ -134,16 +158,4 @@ void __init machine_specific_arch_setup(
 		HYPERVISOR_nmi_op(XENNMI_register_callback, &cb);
 	}
 #endif
-
-	if (HYPERVISOR_xen_version(XENVER_platform_parameters, &pp) == 0)
-		set_fixaddr_top(pp.virt_start);
-
-	machine_to_phys_mapping = (unsigned long *)MACH2PHYS_VIRT_START;
-	machine_to_phys_nr_ents = MACH2PHYS_NR_ENTRIES;
-	if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) {
-		machine_to_phys_mapping = (unsigned long *)mapping.v_start;
-		machine_to_phys_nr_ents = mapping.max_mfn + 1;
-	}
-	while ((1UL << machine_to_phys_order) < machine_to_phys_nr_ents )
-		machine_to_phys_order++;
 }

Index: head-2008-03-11/arch/i386/mm/init-xen.c
===================================================================
@@ -388,9 +388,6 @@
 	unsigned long vaddr;
 	pgd_t *pgd_base = (pgd_t *)xen_start_info->pt_base;
 
-	swapper_pg_dir = pgd_base;
-	init_mm.pgd    = pgd_base;
-
 	/* Enable PSE if available */
 	if (cpu_has_pse) {
 		set_in_cr4(X86_CR4_PSE);