[2/6] Default to bootm_size() when CONFIG_SYS_BOOTMAPSZ is not defined

diff --git a/README b/README
index 21cd71b..b8c1833 100644
--- a/README
+++ b/README
@@ -2311,7 +2311,10 @@  Configuration Settings:
 		used) must be put below this limit, unless "bootm_low"
 		enviroment variable is defined and non-zero. In such case
 		all data for the Linux kernel must be between "bootm_low"
-		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.
+		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.  The environment
+		variable "bootm_mapsize" will override the value of
+		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
+		then the value in "bootm_size" will be used instead.
 
 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
 		Enable initrd_high functionality.  If defined then the
@@ -3147,7 +3150,16 @@  List of environment variables (most likely not complete):
 		  for use by the bootm command. See also "bootm_size"
 		  environment variable. Address defined by "bootm_low" is
 		  also the base of the initial memory mapping for the Linux
-		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ.
+		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
+		  bootm_mapsize.
+
+  bootm_mapsize	- Size of the initial memory mapping for the Linux kernel.
+		  This variable is given as a hexadecimal number and it
+		  defines the size of the memory region starting at base
+		  address bootm_low that is accessible by the Linux kernel
+		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
+		  as the default value if it is defined, and bootm_size is
+		  used otherwise.
 
   bootm_size	- Memory range available for image processing in the bootm
 		  command can be restricted. This variable is given as
diff --git a/arch/powerpc/lib/bootm.c b/arch/powerpc/lib/bootm.c
index 11a574a..1ee4f79 100644
--- a/arch/powerpc/lib/bootm.c
+++ b/arch/powerpc/lib/bootm.c
@@ -95,7 +95,7 @@  static void boot_jump_linux(bootm_headers_t *images)
 		debug ("   Booting using OF flat tree...\n");
 		WATCHDOG_RESET ();
 		(*kernel) ((bd_t *)of_flat_tree, 0, 0, EPAPR_MAGIC,
-			   CONFIG_SYS_BOOTMAPSZ, 0, 0);
+			   getenv_bootm_mapsize(), 0, 0);
 		/* does not return */
 	} else
 #endif
diff --git a/common/image.c b/common/image.c
index c86b86f..a6247d8 100644
--- a/common/image.c
+++ b/common/image.c
@@ -454,6 +454,22 @@  phys_size_t getenv_bootm_size(void)
 #endif
 }
 
+phys_size_t getenv_bootm_mapsize(void)
+{
+	phys_size_t tmp;
+	char *s = getenv ("bootm_mapsize");
+	if (s) {
+		tmp = (phys_size_t)simple_strtoull (s, NULL, 16);
+		return tmp;
+	}
+
+#if defined(CONFIG_SYS_BOOTMAPSZ)
+	return CONFIG_SYS_BOOTMAPSZ;
+#else
+	return getenv_bootm_size();
+#endif
+}
+
 void memmove_wd (void *to, void *from, size_t len, ulong chunksz)
 {
 	if (to == from)
@@ -1207,7 +1223,7 @@  int boot_relocate_fdt (struct lmb *lmb, char **of_flat_tree, ulong *of_size)
 	/* Pad the FDT by a specified amount */
 	of_len = *of_size + CONFIG_SYS_FDT_PAD;
 	of_start = (void *)(unsigned long)lmb_alloc_base(lmb, of_len, 0x1000,
-			CONFIG_SYS_BOOTMAPSZ + getenv_bootm_low());
+			getenv_bootm_mapsize() + getenv_bootm_low());
 
 	if (of_start == 0) {
 		puts("device tree - allocation error\n");
@@ -1581,7 +1597,7 @@  int boot_get_cmdline (struct lmb *lmb, ulong *cmd_start, ulong *cmd_end)
 	char *s;
 
 	cmdline = (char *)(ulong)lmb_alloc_base(lmb, CONFIG_SYS_BARGSIZE, 0xf,
-				     CONFIG_SYS_BOOTMAPSZ + getenv_bootm_low());
+				getenv_bootm_mapsize() + getenv_bootm_base());
 
 	if (cmdline == NULL)
 		return -1;
@@ -1617,7 +1633,7 @@  int boot_get_cmdline (struct lmb *lmb, ulong *cmd_start, ulong *cmd_end)
 int boot_get_kbd (struct lmb *lmb, bd_t **kbd)
 {
 	*kbd = (bd_t *)(ulong)lmb_alloc_base(lmb, sizeof(bd_t), 0xf,
-				     CONFIG_SYS_BOOTMAPSZ + getenv_bootm_low());
+				getenv_bootm_mapsize() + getenv_bootm_low());
 	if (*kbd == NULL)
 		return -1;
 
diff --git a/include/image.h b/include/image.h
index aa1d7df..b77cb79 100644
--- a/include/image.h
+++ b/include/image.h
@@ -451,6 +451,7 @@  int image_check_dcrc (const image_header_t *hdr);
 int getenv_yesno (char *var);
 ulong getenv_bootm_low(void);
 phys_size_t getenv_bootm_size(void);
+phys_size_t getenv_bootm_mapsize(void);
 void memmove_wd (void *to, void *from, size_t len, ulong chunksz);
 #endif