On Tue, Mar 09, 2010 at 09:12:03AM -0500, Prarit Bhargava wrote:

New sockets have on-die memory controllers.  This means that in certain
HW configurations the memory behind the socket comes and goes as the socket
is physically enabled and disabled.

Since the cpu bringup code does on node memory allocations, the memory on the
added socket must be onlined first.

Add a .config option to automatically online hot added memory, and enable it
in the acpi memory add path.

This seems like the right thing to do.

+config ACPI_HOTPLUG_MEMORY_AUTO_ONLINE
+	bool "Automatically online hotplugged memory"
+	depends on ACPI_HOTPLUG_MEMORY
+	default n

default !S390? default x86?

+		result = online_pages(info->start_addr >> PAGE_SHIFT,
+				      info->length >> PAGE_SHIFT);
+		if (!result)
+			set_memory_state(info->start_addr, MEM_ONLINE);
+		else
+			printk("Memory online failed.\n");

That probably wants to be more descriptive and have a loglevel. What 
happens if this fails? The CPU presumably can't be brought up?

-- 
Matthew Garrett | mjg59@srcf.ucam.org