xtensa: nommu: reserve memory below PLATFORM_DEFAULT_MEM_START
Memory accounting code can't handle pages below
PLATFORM_DEFAULT_MEM_START. Reserve those pages if they exist.
When PLATFORM_DEFAULT_MEM_START is zero reserve one page at address 0 to
make sure that successfull memory allocations don't return NULL.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c
index 77ed202..5a084fa 100644
--- a/arch/xtensa/mm/init.c
+++ b/arch/xtensa/mm/init.c
@@ -239,6 +239,17 @@
unsigned long bootmap_start, bootmap_size;
int i;
+ /* Reserve all memory below PLATFORM_DEFAULT_MEM_START, as memory
+ * accounting doesn't work for pages below that address.
+ *
+ * If PLATFORM_DEFAULT_MEM_START is zero reserve page at address 0:
+ * successfull allocations should never return NULL.
+ */
+ if (PLATFORM_DEFAULT_MEM_START)
+ mem_reserve(0, PLATFORM_DEFAULT_MEM_START, 0);
+ else
+ mem_reserve(0, 1, 0);
+
sysmem_dump();
max_low_pfn = max_pfn = 0;
min_low_pfn = ~0;