Boot-related documentation update

- document 'bootm_low' and 'bootm_size' environment variables
- update inaccurate CFG_BOOTMAPSZ entry

Signed-off-by: Bartlomiej Sieka <tur@semihalf.com>

diff --git a/README b/README
index 7c1634580a28c054a8b5f5955bfa62920e944b24..3a10bd762b5d6af892eecec09eae2276aabae97c 100644 (file)
--- a/README
+++ b/README
@@ -1997,8 +1997,11 @@ Configuration Settings:
 - CFG_BOOTMAPSZ:
                Maximum size of memory mapped by the startup code of
                the Linux kernel; all data that must be processed by
-               the Linux kernel (bd_info, boot arguments, eventually
-               initrd image) must be put below this limit.
+               the Linux kernel (bd_info, boot arguments, FDT blob if
+               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" + CFG_BOOTMAPSZ.
 
 - CFG_MAX_FLASH_BANKS:
                Max number of Flash memory banks
@@ -2743,6 +2746,20 @@ Some configuration options can be set using Environment Variables:
 
   bootfile     - Name of the image to load with TFTP
 
+  bootm_low    - Memory range available for image processing in the bootm
+                 command can be restricted. This variable is given as
+                 a hexadecimal number and defines lowest address allowed
+                 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 descripton of CFG_BOOTMAPSZ.
+
+  bootm_size   - Memory range available for image processing in the bootm
+                 command can be restricted. This variable is given as
+                 a hexadecimal number and defines the size of the region
+                 allowed for use by the bootm command. See also "bootm_low"
+                 environment variable.
+
   autoload     - if set to "no" (any string beginning with 'n'),
                  "bootp" will just load perform a lookup of the
                  configuration from the BOOTP server, but not try to