RE: [PATCH] long format VHPT

["Chen, Kenneth W" <kenneth.w.chen@intel.com>]

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Arun Sharma wrote:
> - Can we avoid allocating VHPTs for non-existent CPUs ?
> - How about calling alloc_bootmem on cpu0 and __get_free_pages
>   on secondary cpus ?

> I noticed that when we hit ia64_mmu_init() on a secondary
> processor, cpu0 has already made successful calls to 
> __get_free_pages(). But calls from the secondary cpus fail.
> Does anyone know why ?

I did some hacking over the weekend. VHPT allocation can be done
from boot processor in function do_boot_cpu() before waking up
secondary CPUs.  Allocation can be easily made numa friendly by
calling alloc_pages_node (didn't bother to do that for now).

- Ken

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diff -Nurp 2.6.0-test5.v/arch/ia64/kernel/smpboot.c 2.6.0-test5.ken/arch/ia64/kernel/smpboot.c
--- 2.6.0-test5.v/arch/ia64/kernel/smpboot.c	Sun Sep 28 16:28:16 2003
+++ 2.6.0-test5.ken/arch/ia64/kernel/smpboot.c	Sun Sep 28 16:32:24 2003
@@ -358,11 +358,16 @@ fork_by_hand (void)
 	return copy_process(CLONE_VM|CLONE_IDLETASK, 0, 0, 0, NULL, NULL);
 }
 
+#ifdef CONFIG_IA64_LONG_FORMAT_VHPT
+extern unsigned long vhpt_base[NR_CPUS];
+#endif
+
 static int __init
 do_boot_cpu (int sapicid, int cpu)
 {
 	struct task_struct *idle;
 	int timeout;
+	struct page * vhpt_page;
 
 	/*
 	 * We can't use kernel_thread since we must avoid to reschedule the child.
@@ -382,6 +387,16 @@ do_boot_cpu (int sapicid, int cpu)
 
 	task_for_booting_cpu = idle;
 
+#ifdef CONFIG_IA64_LONG_FORMAT_VHPT
+	vhpt_page = alloc_pages(__GFP_HIGHMEM, LONG_VHPT_BITS - PAGE_SHIFT);
+	if (vhpt_page)
+		vhpt_base[cpu] = (unsigned long) page_address(vhpt_page);
+	else
+		return -EINVAL;
+	printk(KERN_INFO "CPU %d: Long format VHPT initialised at base address:"
+			 " 0x%lx\n", cpu, vhpt_base[cpu]);
+#endif
+
 	Dprintk("Sending wakeup vector %lu to AP 0x%x/0x%x.\n", ap_wakeup_vector, cpu, sapicid);
 
 	platform_send_ipi(cpu, ap_wakeup_vector, IA64_IPI_DM_INT, 0);
@@ -404,6 +419,7 @@ do_boot_cpu (int sapicid, int cpu)
 		printk(KERN_ERR "Processor 0x%x/0x%x is stuck.\n", cpu, sapicid);
 		ia64_cpu_to_sapicid[cpu] = -1;
 		cpu_clear(cpu, cpu_online_map);  /* was set in smp_callin() */
+		__free_pages(vhpt_page, LONG_VHPT_BITS - PAGE_SHIFT);
 		return -EINVAL;
 	}
 	return 0;
diff -Nurp 2.6.0-test5.v/arch/ia64/mm/init.c 2.6.0-test5.ken/arch/ia64/mm/init.c
--- 2.6.0-test5.v/arch/ia64/mm/init.c	Sun Sep 28 16:28:22 2003
+++ 2.6.0-test5.ken/arch/ia64/mm/init.c	Sun Sep 28 16:32:25 2003
@@ -344,11 +344,8 @@ ia64_mmu_init (void *my_cpu_data)
 	if (cpu == 0)
 	{
 		/* We allocate all VHPTs here as we may not have enough contiguous memory later */
-		/* Also, we cannot use __get_free_pages on the target processor (until after init_cpu) */
-		for (i = 0; i < NR_CPUS; i++){
-			vhpt_base[i] = (unsigned long)__alloc_bootmem(LONG_VHPT_SIZE, LONG_VHPT_SIZE, __pa(MAX_DMA_ADDRESS));
-			printk(KERN_INFO "CPU %d: Long format VHPT initialised at base address: 0x%lx\n", i, vhpt_base[i]);
-		}
+		vhpt_base[0] = (unsigned long)__alloc_bootmem(LONG_VHPT_SIZE, LONG_VHPT_SIZE, __pa(MAX_DMA_ADDRESS));
+		printk(KERN_INFO "CPU 0: Long format VHPT initialised at base address: 0x%lx\n", vhpt_base[0]);
 	}
 #endif