+#ifdef RESERVE_HOTADD
+/*
+ * Protect against too large hotadd areas that would fill up memory.
+ */
+static int hotadd_enough_memory(struct bootnode *nd)
+{
+ static unsigned long allocated;
+ static unsigned long last_area_end;
+ unsigned long pages = (nd->end - nd->start) >> PAGE_SHIFT;
+ long mem = pages * sizeof(struct page);
+ unsigned long addr;
+ unsigned long allowed;
+ unsigned long oldpages = pages;
+
+ if (mem < 0)
+ return 0;
+ allowed = (end_pfn - e820_hole_size(0, end_pfn)) * PAGE_SIZE;
+ allowed = (allowed / 100) * hotadd_percent;
+ if (allocated + mem > allowed) {
+ unsigned long range;
+ /* Give them at least part of their hotadd memory upto hotadd_percent
+ It would be better to spread the limit out
+ over multiple hotplug areas, but that is too complicated
+ right now */
+ if (allocated >= allowed)
+ return 0;
+ range = allowed - allocated;
+ pages = (range / PAGE_SIZE);
+ mem = pages * sizeof(struct page);
+ nd->end = nd->start + range;
+ }
+ /* Not completely fool proof, but a good sanity check */
+ addr = find_e820_area(last_area_end, end_pfn<<PAGE_SHIFT, mem);
+ if (addr == -1UL)
+ return 0;
+ if (pages != oldpages)
+ printk(KERN_NOTICE "SRAT: Hotadd area limited to %lu bytes\n",
+ pages << PAGE_SHIFT);
+ last_area_end = addr + mem;
+ allocated += mem;
+ return 1;
+}
+
+/*
+ * It is fine to add this area to the nodes data it will be used later
+ * This code supports one contigious hot add area per node.
+ */
+static int reserve_hotadd(int node, unsigned long start, unsigned long end)
+{
+ unsigned long s_pfn = start >> PAGE_SHIFT;
+ unsigned long e_pfn = end >> PAGE_SHIFT;
+ int changed = 0;
+ struct bootnode *nd = &nodes_add[node];
+
+ /* I had some trouble with strange memory hotadd regions breaking
+ the boot. Be very strict here and reject anything unexpected.
+ If you want working memory hotadd write correct SRATs.
+
+ The node size check is a basic sanity check to guard against
+ mistakes */
+ if ((signed long)(end - start) < NODE_MIN_SIZE) {
+ printk(KERN_ERR "SRAT: Hotplug area too small\n");
+ return -1;
+ }
+
+ /* This check might be a bit too strict, but I'm keeping it for now. */
+ if (e820_hole_size(s_pfn, e_pfn) != e_pfn - s_pfn) {
+ printk(KERN_ERR "SRAT: Hotplug area has existing memory\n");
+ return -1;
+ }
+
+ if (!hotadd_enough_memory(&nodes_add[node])) {
+ printk(KERN_ERR "SRAT: Hotplug area too large\n");
+ return -1;
+ }
+
+ /* Looks good */
+
+ found_add_area = 1;
+ if (nd->start == nd->end) {
+ nd->start = start;
+ nd->end = end;
+ changed = 1;
+ } else {
+ if (nd->start == end) {
+ nd->start = start;
+ changed = 1;
+ }
+ if (nd->end == start) {
+ nd->end = end;
+ changed = 1;
+ }
+ if (!changed)
+ printk(KERN_ERR "SRAT: Hotplug zone not continuous. Partly ignored\n");
+ }
+
+ if ((nd->end >> PAGE_SHIFT) > end_pfn)
+ end_pfn = nd->end >> PAGE_SHIFT;
+
+ if (changed)
+ printk(KERN_INFO "SRAT: hot plug zone found %Lx - %Lx\n", nd->start, nd->end);
+ return 0;
+}
+#endif
+