[PATCH] 2/6 Make CONFIG_NUMA work on non-numa machines.

From Andy Whitcroft

A few very simple changes in order to make CONFIG_NUMA work everywhere, so
the distros can build one common binary kernel for distributions.

arch/i386/Kconfig

@@ -488,7 +488,7 @@ config NR_CPUS
 # Common NUMA Features
 config NUMA
 	bool "Numa Memory Allocation Support"
-	depends on (HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT && ACPI && !ACPI_HT_ONLY)))
+	depends on (HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT && ACPI && !ACPI_HT_ONLY))) || X86_PC
 
 config DISCONTIGMEM
 	bool

arch/i386/kernel/smpboot.c

@@ -966,6 +966,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
 		if (APIC_init_uniprocessor())
 			printk(KERN_NOTICE "Local APIC not detected."
 					   " Using dummy APIC emulation.\n");
+		map_cpu_to_logical_apicid();
 		return;
 	}
 

arch/i386/mm/discontig.c

@@ -81,6 +81,36 @@ unsigned long node_remap_offset[MAX_NUMNODES];
 void *node_remap_start_vaddr[MAX_NUMNODES];
 void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags);
 
+/*
+ * FLAT - support for basic PC memory model with discontig enabled, essentially
+ *        a single node with all available processors in it with a flat
+ *        memory map.
+ */
+void __init get_memcfg_numa_flat(void)
+{
+	int pfn;
+
+	printk("NUMA - single node, flat memory mode\n");
+
+	/* Run the memory configuration and find the top of memory. */
+	find_max_pfn();
+	node_start_pfn[0]  = 0;
+	node_end_pfn[0]	  = max_pfn;
+
+	/* Fill in the physnode_map with our simplistic memory model,
+	* all memory is in node 0.
+	*/
+	for (pfn = node_start_pfn[0]; pfn <= node_end_pfn[0];
+	       pfn += PAGES_PER_ELEMENT)
+	{
+		physnode_map[pfn / PAGES_PER_ELEMENT] = 0;
+	}
+
+         /* Indicate there is one node available. */
+	node_set_online(0);
+	numnodes = 1;
+}
+
 /*
  * Find the highest page frame number we have available for the node
  */

include/asm-i386/mmzone.h

@@ -122,6 +122,9 @@ static inline struct pglist_data *pfn_to_pgdat(unsigned long pfn)
 #include <asm/numaq.h>
 #elif CONFIG_X86_SUMMIT
 #include <asm/srat.h>
+#elif CONFIG_X86_PC
+#define get_memcfg_numa get_memcfg_numa_flat
+#define get_zholes_size(n) (0)
 #else
 #define pfn_to_nid(pfn)		(0)
 #endif /* CONFIG_X86_NUMAQ */