From: Shaohui Zheng Add add_memory interface to support to memory hotplug emulation for each online node under debugfs. The reserved memory can be added into desired node with this interface. The layout on debugfs: mem_hotplug/node0/add_memory mem_hotplug/node1/add_memory mem_hotplug/node2/add_memory ... Add a memory section(128M) to node 3(boots with mem=1024m) echo 0x40000000 > mem_hotplug/node3/add_memory CC: David Rientjes CC: Dave Hansen Signed-off-by: Haicheng Li Signed-off-by: Shaohui Zheng --- Index: linux-hpe4/mm/memory_hotplug.c =================================================================== --- linux-hpe4.orig/mm/memory_hotplug.c 2010-12-10 13:22:44.753331000 +0800 +++ linux-hpe4/mm/memory_hotplug.c 2010-12-10 13:41:48.803331000 +0800 @@ -933,6 +933,81 @@ static struct dentry *memhp_debug_root; +#ifdef CONFIG_ARCH_MEMORY_PROBE + +static ssize_t add_memory_store(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + u64 phys_addr = 0; + int nid = file->private_data - NULL; + int ret; + + printk(KERN_INFO "Add a memory section to node: %d.\n", nid); + phys_addr = simple_strtoull(buf, NULL, 0); + + ret = add_memory(nid, phys_addr, PAGES_PER_SECTION << PAGE_SHIFT); + if (ret) + count = ret; + + return count; +} + +static int add_memory_open(struct inode *inode, struct file *file) +{ + file->private_data = inode->i_private; + return 0; +} + +static const struct file_operations add_memory_file_ops = { + .open = add_memory_open, + .write = add_memory_store, + .llseek = generic_file_llseek, +}; + +/* + * Create add_memory debugfs entry under specified node + */ +static int debugfs_create_add_memory_entry(int nid) +{ + char buf[32]; + static struct dentry *node_debug_root; + + snprintf(buf, sizeof(buf), "node%d", nid); + node_debug_root = debugfs_create_dir(buf, memhp_debug_root); + if (!node_debug_root) + return -ENOMEM; + + /* the nid information was represented by the offset of pointer(NULL+nid) */ + if (!debugfs_create_file("add_memory", S_IWUSR, node_debug_root, + NULL + nid, &add_memory_file_ops)) + return -ENOMEM; + + return 0; +} + +static int __init memory_debug_init(void) +{ + int nid; + + if (!memhp_debug_root) + memhp_debug_root = debugfs_create_dir("mem_hotplug", NULL); + if (!memhp_debug_root) + return -ENOMEM; + + for_each_online_node(nid) + debugfs_create_add_memory_entry(nid); + + return 0; +} + +module_init(memory_debug_init); +#else +static debugfs_create_add_memory_entry(int nid) +{ + return 0; +} +#endif /* CONFIG_ARCH_MEMORY_PROBE */ + static ssize_t add_node_store(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { @@ -963,6 +1038,8 @@ return -ENOMEM; ret = add_memory(nid, start, size); + + debugfs_create_add_memory_entry(nid); return ret ? ret : count; } Index: linux-hpe4/Documentation/memory-hotplug.txt =================================================================== --- linux-hpe4.orig/Documentation/memory-hotplug.txt 2010-12-10 13:22:44.733331000 +0800 +++ linux-hpe4/Documentation/memory-hotplug.txt 2010-12-10 13:42:12.783331002 +0800 @@ -19,6 +19,7 @@ 4.1 Hardware(Firmware) Support 4.2 Notify memory hot-add event by hand 4.3 Node hotplug emulation + 4.4 Memory hotplug emulation 5. Logical Memory hot-add phase 5.1. State of memory 5.2. How to online memory @@ -239,6 +240,25 @@ Once the new node has been added, it is possible to online the memory by toggling the "state" of its memory section(s) as described in section 5.1. +4.4 Memory hotplug emulation +------------ +With debugfs, it is possible to test memory hotplug with software method, we +can add memory section to desired node with add_memory interface. It is a much +more powerful interface than "probe" described in section 4.2. + +There is an add_memory interface for each online node at the debugfs mount +point. + mem_hotplug/node0/add_memory + mem_hotplug/node1/add_memory + mem_hotplug/node2/add_memory + ... + +Add a memory section(128M) to node 3(boots with mem=1024m) + + echo 0x40000000 > mem_hotplug/node3/add_memory + +Once the new memory section has been added, it is possible to online the memory +by toggling the "state" described in section 5.1. ------------------------------ 5. Logical Memory hot-add phase -- Thanks & Regards, Shaohui -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/