X-Git-Url: http://git.ipfire.org/?a=blobdiff_plain;f=doc%2FREADME.b4860qds;h=eada0c7dd89b55d7be39bc500c241dd491e6eaa4;hb=bc55c07a2bc8435d427707d96b3b08fe1fa00198;hp=3da77d9f0f83a000e1676cf00d11c553cc4ed046;hpb=c4d376fd1c2bce8d64cec0431dd3f24957b6dec4;p=people%2Fms%2Fu-boot.git

diff --git a/doc/README.b4860qds b/doc/README.b4860qds
index 3da77d9f0f..eada0c7dd8 100644
--- a/doc/README.b4860qds
+++ b/doc/README.b4860qds
@@ -328,3 +328,39 @@ The below commands apply to both B4860QDS and B4420QDS.
    On Linux the interfaces are renamed as:
 	. eth2 -> fm1-gb2
 	. eth3 -> fm1-gb3
+
+NAND boot with 2 Stage boot loader
+----------------------------------
+PBL initialise the internal SRAM and copy SPL(160KB) in SRAM.
+SPL further initialise DDR using SPD and environment variables and copy
+u-boot(768 KB) from flash to DDR.
+Finally SPL transer control to u-boot for futher booting.
+
+SPL has following features:
+ - Executes within 256K
+ - No relocation required
+
+ Run time view of SPL framework during  boot :-
+ -----------------------------------------------
+ Area        | Address                         |
+-----------------------------------------------
+ Secure boot | 0xFFFC0000 (32KB)               |
+ headers     |                                 |
+ -----------------------------------------------
+ GD, BD      | 0xFFFC8000 (4KB)                |
+ -----------------------------------------------
+ ENV         | 0xFFFC9000 (8KB)                |
+ -----------------------------------------------
+ HEAP        | 0xFFFCB000 (30KB)               |
+ -----------------------------------------------
+ STACK       | 0xFFFD8000 (22KB)               |
+ -----------------------------------------------
+ U-boot SPL  | 0xFFFD8000 (160KB)              |
+ -----------------------------------------------
+
+NAND Flash memory Map on B4860 and B4420QDS
+------------------------------------------
+ Start		 End		Definition			Size
+0x000000	0x0FFFFF	u-boot                          1MB
+0x140000	0x15FFFF	u-boot env                      128KB
+0x1A0000	0x1BFFFF	FMAN Ucode                      128KB