From: Max Filippov <jcmvbkbc@gmail.com>
Date: Fri, 3 Oct 2014 23:46:34 +0000 (+0400)
Subject: xtensa: nommu: reserve memory below PLATFORM_DEFAULT_MEM_START
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=566fb58ed422537715023d1f19b705247a640b11;p=linux-beck.git

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 77ed20209ca5..5a084fa5b608 100644
--- a/arch/xtensa/mm/init.c
+++ b/arch/xtensa/mm/init.c
@@ -239,6 +239,17 @@ void __init bootmem_init(void)
 	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;