diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 703c7c2e0d9fb4d9ee7de4ac4b199e4d9cde2792..4ec900af332f0656ed4a847970b57bb8d66761ed 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -82,6 +82,11 @@ extern struct task_struct *current_set[NR_CPUS];
 int __map_without_bats;
 int __map_without_ltlbs;
 
+/*
+ * This tells the system to allow ioremapping memory marked as reserved.
+ */
+int __allow_ioremap_reserved;
+
 /* max amount of low RAM to map in */
 unsigned long __max_low_memory = MAX_LOW_MEM;
 
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 9aa39fe74f8aba4ace870a78da94e900225d94ec..34dacc32250df81d0bfebbb0f5f24df1b5abec24 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -115,6 +115,7 @@ extern void settlbcam(int index, unsigned long virt, phys_addr_t phys,
 extern void invalidate_tlbcam_entry(int index);
 
 extern int __map_without_bats;
+extern int __allow_ioremap_reserved;
 extern unsigned long ioremap_base;
 extern unsigned int rtas_data, rtas_size;
 
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index b55bbe87acb83426bd0fabbd22225d28598cf8d7..177e4038b43c7a6044d52c170faa1502241d01f9 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -26,6 +26,7 @@
 #include <linux/vmalloc.h>
 #include <linux/init.h>
 #include <linux/highmem.h>
+#include <linux/lmb.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -191,7 +192,8 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, unsigned long flags,
 	 * Don't allow anybody to remap normal RAM that we're using.
 	 * mem_init() sets high_memory so only do the check after that.
 	 */
-	if (mem_init_done && (p < virt_to_phys(high_memory))) {
+	if (mem_init_done && (p < virt_to_phys(high_memory)) &&
+	    !(__allow_ioremap_reserved && lmb_is_region_reserved(p, size))) {
 		printk("__ioremap(): phys addr 0x%llx is RAM lr %p\n",
 		       (unsigned long long)p, __builtin_return_address(0));
 		return NULL;
diff --git a/include/linux/lmb.h b/include/linux/lmb.h
index 2442e3f3d03335ff5e515d0876f64cadfa3f6dbe..ef82b8fcbddbdf169d9c71eae0db4b78c5e4b110 100644
--- a/include/linux/lmb.h
+++ b/include/linux/lmb.h
@@ -54,6 +54,7 @@ extern u64 __init lmb_phys_mem_size(void);
 extern u64 lmb_end_of_DRAM(void);
 extern void __init lmb_enforce_memory_limit(u64 memory_limit);
 extern int __init lmb_is_reserved(u64 addr);
+extern int lmb_is_region_reserved(u64 base, u64 size);
 extern int lmb_find(struct lmb_property *res);
 
 extern void lmb_dump_all(void);
diff --git a/lib/lmb.c b/lib/lmb.c
index 0343c05609f0d62f9b48b259bf3018db728b11a5..9cee17142b2cdc6d2d7a78c8b6ca5fd6573eb4b8 100644
--- a/lib/lmb.c
+++ b/lib/lmb.c
@@ -263,7 +263,7 @@ long __init lmb_reserve(u64 base, u64 size)
 	return lmb_add_region(_rgn, base, size);
 }
 
-long __init lmb_overlaps_region(struct lmb_region *rgn, u64 base, u64 size)
+long lmb_overlaps_region(struct lmb_region *rgn, u64 base, u64 size)
 {
 	unsigned long i;
 
@@ -493,6 +493,11 @@ int __init lmb_is_reserved(u64 addr)
 	return 0;
 }
 
+int lmb_is_region_reserved(u64 base, u64 size)
+{
+	return lmb_overlaps_region(&lmb.reserved, base, size);
+}
+
 /*
  * Given a <base, len>, find which memory regions belong to this range.
  * Adjust the request and return a contiguous chunk.